Tyranid Void-Faring Organisms


Were the Tyranids only terrestrial organisms, their terror would not be so great, for without ships to carry them from world to world, no creature is terrible on a galactic scale. The Tyranids, however, are far more than beasts the size of men and tanks.
They exist in the void as well, vast creatures many miles long, whose natural defences are
equivalent to the Lances and Macrobatteries of starships, and who can only really be referred to as Bio-Ships. Their mass is surpassed only by their menace, for they are true void-born predators, as deadly to starships as the apex predators of many worlds are to human beings.
In game terms, Tyranid bio-ships function in much the same way normal vessels do, though with a few significant conceptual differences. Most importantly, a Tyranid vessel‘s Hull Integrity represents its physical constitution, its ability to withstand harm, more akin to a creature‘s wound score than a starship‘s Hull Integrity, though on a scale dwarfing even the largest Bio-titan.
Similarly, Detection and Manoeuvrability represent the capabilities of a creature, rather than a machine operated by a vast crew of people. Tyranid ships do not generate power in any conventional sense, but similarly do not consume it. Finally, bio-ships are not crewed – the organisms that roam the creature‘s bodily cavities are more akin to an immune system than a crew compliment, and deep within the heart of the organism are spawning chambers were
yet more creatures can be spawned at a moment‘s notice, giving the bio-ship an essentially limitless supply of warrior creatures to board enemy vessels and assault the surface of a world. The precise details of what these differences mean are described below.

Tyranid Specific Rules

Crew and Morale

  • Bio-ships have neither of these things.
    • A bio-ship‘s Crew rating is always 100 (because the ship controls everything) and cannot be reduced in any way. A bio-ship‘s
    • Morale rating is similarly always 100 (because the creatures on board are essentially mindless, frenzied monsters, contained within a creature that considers enemy boarders in much the same way a human might consider a minor illness or parasitic infestation – annoying).
  • Synaptic Control and Instinctive Behaviour
    • All Tyranid Bio-Ships have a Willpower characteristic, which functions exactly like the Willpower characteristic of a character.
    • Every Strategic Turn, a bio-ship may attempt a Willpower Test. If it passes, it may act freely, using whatever connection to the Hive Mind it can muster to direct its actions. If it fails or does not test, the bio- ship reverts to its natural, usually predatory, instincts, which are described below, which partially determine the actions it must take.
    • A ship acting under the control of the Hive Mind (because it passed its Willpower Test) may perform up to three actions in any turn – one of these must be a Manoeuvre
      Action, up to one may be a shooting action, and the third may be an extended action
      (some Tyranid-specific examples of which are described later). These may be chosen
      freely, as the creature‘s instincts have been overridden by the will of the Hive Mind.
    • A ship that is acting on instinct has significantly less freedom of action, and the
      following list of conditions must be considered to determine that action. If a
      particular action type is not listed for a particular condition, it may be used freely,
      though a bio-ship acting on instinct will only ever fire upon the nearest enemy vessel.
  1. Will a normal Manoeuvre Action take the bio-ship into a gas or dust cloud, asteroid
    field, planetary rings, minefield, warp rift or other dangerous stellar phenomena?
    • If yes, then the ship must move and turn in order to turn away from and
      avoid the stellar phenomenon.
    • If no, then continue to condition 2.
  2. Is there an enemy vessel within the front arc of the bio-ship and 2 VU or less away?
    • If yes, then the bio-ship must attempt to close and ram, perform a boarding action, or
      use a melee weapon symbiote. If the bio-ship has functioning Bio-plasma weapon symbiotes, it may ignore this condition. If this condition is ignored, or if there is no enemy vessel within the front arc and within range, then continue to condition 3.
  3. Is the nearest enemy vessel within the front arc of the bio-ship and more than 10 VU
    away?
    • If yes, then the bio-ship must move as fast as possible (using its Manoeuvre Action
      and Extended Action to increase the distance travelled) directly towards that vessel. If not, then continue to condition 4.
  4. This condition only applies to Escort Droneships, Vanguard Droneships and Kraken. Is the
    nearest enemy vessel within the bio-ship‘s rear arc?
    • If yes, then the bio-ship must use the Come to New Heading Manoeuvre Action to turn towards the enemy ship.
    • If no, or if this condition does not apply to the bio-ship, continue to condition 5.
  5. Is there an enemy vessel within the front arc and within range of functioning
    weapon symbiotes?
    • If yes, then the bio-ship must perform the Lock On Target Extended Action, may not
      turn, and must fire every available weapon at the target vessel. If no, then continue to
      condition 6.
  6. None of the above conditions apply.
    • If there is a planet within 20 VU, then the bio-ship must move towards that
      if possible.
    • If there is no planet within that distance, then the bio-ship moves directly forwards at half speed without turning.

Navigation

Bio-ships are engineered void-dwelling predators, creatures for which asteroid fields and nebulae are as natural as grass is to a Groxen. Navigating the void by their own instincts, or by the will of the Hive Mind, bio-ships are naturally adept at eluding the hazards of their habitat.
For all bio-ships, the number listed in brackets after their Detection and Manoeuvrability values are the total characteristics (already including the bonuses for Detection and Manoeuvrability,
respectively) against which all relevant tests are made. In any situation where an action
requires a Detection test of some sort, it will use that value, and likewise any situation
requiring a test involving Manoeuvrability will use the value listed in brackets.

Targeting

All bio-ships have a listed Ballistic Skill characteristic. This functions in a manner identical to the Ballistic Skill characteristic possessed by characters, and is used in the same way – to determine
whether or not ranged attacks hit their intended target. All ranged attacks performed by a given bio-ship use the listed Ballistic Skill value.
Tyranid bio-weapon locations are slightly different to those found on conventional vessels, and have fire arcs determined as follows. The specific fire arcs for different weapon symbiotes on different bio-ships are noted in their respective entries.

Boarding

Bio-ships are hostile environs, filled with fanged and clawed monstrosities engineered to do only one thing: kill.
Attempts to board bio-ships are seldom successful, and the defence against a Tyranid boarding action are hard-fought and costly affairs.
Tyranid vessels will never voluntarily attempt to break free from a boarding action unless compelled to do so by the Hive Mind – their predatory instincts drive them to assault the enemy, and retreating from that is contrary to those instincts. Similarly, a Tyranid vessel will not accept the surrender of a crew who have been demoralised to the point of defeat by a boarding action – the creatures continue to hunt and kill until there is nothing left.
In place of a Command Test (which, given their lack of actual crew, bio-ships tend not to have), bio-ships have a Boarding Value, which is tested against in all boarding actions and Hit-and-Run attacks. Crew rating and remaining hull integrity modify this value in the same way that they modify Command Tests for non-Tyranids.
Attempts to perform Hit-and-Run attacks against bio-ships are more difficult. Should the Hit-and-Run attack be successful, the vast and deadly anatomy of the bio-ship makes it difficult to select an appropriate target to attack. When rolling to determine which critical hit is inflicted, the lowest result of the two rolls, not the highest, should be selected.

Extended Actions

Many of the normal Extended Actions listed in the Rogue Trader rulebook refer to
things like Tech-Use Tests, or relate to the crew. Neither of these things are appropriate
to the organic and singular nature of bio- ships. The following Extended Actions cover
activities more appropriate to a void-swimming predator.

Careful Advance
The bio-ship takes particular care as it advances; concentrating on the manoeuvres
it must perform. It must make a Challenging (+0) Willpower Test to focus in this manner. If it succeeds, it may add +5 to its Manoeuvrability for the remainder of the turn. For every two degrees of success, it may add an additional +5.

Focus on Prey
The bio-ship makes a Challenging (+0) Detection Test to concentrate all of its efforts on a single enemy vessel. If successful, add +5 to the Ballistic Skill Test to fire one Weapon Symbiote during this turn. Every two additional degrees of success add an additional +5 to the same Test.

Heal Injuries
The bio-ship makes a Difficult (-10) Willpower Test to direct organisms around its body that will heal its wounds. If it succeeds, it repairs a single depressurised or wounded Vital Organ or Symbiote. This normally takes 1d5 turns, however, this can be reduced by one turn per degree of success to a minimum of 1 turn. Destroyed Vital Organs or Symbiotes cannot be healed in
this way.

Hit and Run
This action can only be performed if the bio-ship has Launch Bays or Torpedoes. The bio-ship sends out a variety of lesser creatures, from metal-eating borer worms the size of battle tanks, to carrier beasts containing swarms of brood creatures. In a single action, a bio-ship may make a number of Hit-and-Run attempts equal to the number of Launch Bays and Torpedo
weapon symbiotes it possesses.
Each such weapon symbiote has an Accuracy value. The bio-ship must roll equal to or less than this value on d100 in order for the boarding creatures to reach their target, which must be within 5 VU. Success means that one boarding creature reached the target. Every degree of success on this test allows for an additional boarding creature to reach the target vessel, up to a maximum
number equal to the weapon symbiotes‘ strength (so a Strength 4 torpedo weapon symbiote can allow for up to 4 boarding creatures to reach the target, if 3 degrees of success are scored). Launch bay weapon symbiotes must be combined into a single symbiote for the purposes of this test, but every Torpedo weapon symbiote is used separately. If the Accuracy Test is failed,
then the wave of boarding creatures was crippled, lost or destroyed en-route. Turrets
impose a penalty on this test as they do with all Hit-and-Run attacks.
For every wave where one or more boarding creatures successfully reach their target, make an Ordinary (+10) Boarding Value Test opposed by the Command Test of the leader of the defending troops (the Boarding Value is the same as that of the bio-ship the boarding creatures originated from). The Tyranids gain an additional +10 on the Boarding Value Test for every
additional creature within that wave that reached the target, as ever-greater numbers
of Tyranids begin to tear through the ship. If the Tyranids succeed, roll 1d5+1 on the
Critical Hit table twice and pick the highest result to apply to the highest ship, plus 1
point of damage to Hull Integrity for every degree of success. Failure indicates that the
boarding creatures were driven back and destroyed.
Where multiple waves of boarding creatures are sent out, resolve each separately.

Immune Response
As enemies approach, the bio-ship spawns new horrors to repel them. The bio-ship must make a Challenging (+0) Willpower Test. If it succeeds, it may add +10 to its Boarding Value for any opposed tests it makes against enemy boarders during subsequent turns of combat, plus an
additional +5 for every degree of success.
While additional tests are not required in subsequent turns, the bonus will be lost if this action is not performed during a turn.

Swift Advance
The bio-ship makes a Challenging (+0) Willpower Test to force its discharge vents and impellor vanes to propel it more swiftly. If successful, the bio-ship may move an additional VU of movement. Every degree of success allows an additional VU of movement. Failure by 2 or more degrees means that the strain has damaged something, causing an immediate Impellor Vanes Crippled critical.

Watchful
The bio-ship takes stock of its surroundings as it moves; warily searching for the enemies it may encounter or the prey it may find. It must make a Challenging (+0) Willpower Test to focus in this manner. If it succeeds, it may add +5 to its Detection for the remainder of the turn. For every two
degrees of success, it may add an additional +5.

Damage, Crippled Bio-Ships and Critical Hits

The nature of a bio-ship makes it quite different to normal vessels when it comes to
damage. Rather than crucial systems, a bio-ship has an array of Vital Organs and
Symbiotes – the former being integral to the creature‘s ability to function, the latter being
additional semi-autonomous creatures bonded to it to serve specific purposes.
Equivalents to these are present on all bio-ships, so they are listed here for convenience.

A bio-ship‘s Vital Organs are as follows:

  • Circulatory and Respiratory System – these are utterly vital to the survival of a bio-ship, pumping blood-like ichor around its vast body to supply its organs with oxygen. Alongside several dozen or even several hundred hearts, oxygen storage sacs are scattered throughout the creature‘s structure, containing the water and atmosphere drained from previously consumed worlds and that reclaimed through the photosynthesis the bio-ship can perform when approaching a system and coming out of hibernation.
  • Spore Cysts – these great hardened vents in the bio-ship‘s outer skin pump out massive clouds of spores which linger near the ship, absorbing weapons fire and attacking anything within a few hundred metres which might threaten the bio-ship, from attack craft and torpedoes to micro-meteors and other debris, eating through them with a variety of acids and corrosive enzymes until nothing remains. Most bio-ships have one or more Spore Cysts, though Kraken are notable for having none and relying on sheer resilience to withstand attack.
  • Biomass Stores – cavernous stomachs filled with great pools of stinking biological matter are scattered throughout a bio-ship. In Hive Ships, these are utterly immense, connected to a range of capillary tubes and feeder probes which snake down to draw matter up from the surface of planets through vast capillary towers grown by spore bombardment. In other vessels, these mass reserves are less significant, used as emergency food stores and as the raw material for the massive numbers of creatures spawned by the ships.
  • Nervous System – bio-ships are too large to have a single central brain; the size of their bodies would delay signals sent along the nerves too such a degree that a centralised brain would take tens of seconds, or even a few minutes, to consciously respond to stimuli. Instead, a more diffuse system is used to control a bio-ship, with nerve clusters located in key positions all across the ship to direct its actions.
  • Synapse Node – all Tyranids have some form of synapse node, even if only one capable of receiving a signal. In bio-ships, this node acts as both receiver for the higher signals of the Hive Mind (either directly, in the case of Hive Ships and Vanguard Droneships, or indirectly in the case of everything else) and a transmitter of those signals to lesser organisms (in the case of true Synapse Creatures, this allows them to command other creatures over great distances, in the case of most bio-ships, this allows them to control the various symbiotic creatures that their bodies are comprised of at faster-than-light speeds, avoiding one of the issues of a large and diffuse nervous system. A bio-ship with no Synapse Node cannot receive the Hive Mind‘s instructions and will only ever act on instinct.
  • Sensory Network – in space, eyes and ears are frankly rather pointless. Instead, bio-ships are theorised to sense incredibly small changes in electromagnetic radiation and heat, as well as making use of psychic perception, to detect their prey. This network of sensors is roughly analogous to the Augur and Auspex arrays on Imperial vessels.
  • Discharge Vents and Impellor Vanes – these ports and vents all across the surface of the creature give it the ability to move through space, using super-heated gas exhaust and a number of theorised but largely unknown means to propel the bio-ship through the void.

When a symbiote or vital organ is wounded, its function is stopped, but it can be healed given time and effort. Destroyed symbiotes and vital organs are masses of ruined flesh and vile fluids which are beyond swift repair, but which may re-grow or be replaced in time.
Depressurisation doesn‘t particularly harm the creatures present – few Tyranids that exist aboard a bio-ship are particularly reliant on an atmosphere to survive, and there are always more to be spawned – but the sudden exposure to the cold and pressureless void shuts them down to avoid further damage until internal pressure can be returned to normal.

When crippled, the presence of biological systems works to preserve as many of the vital parts of the bio-ship as possible, while ignoring entirely the superfluous ones. This is a form of natural defence mechanism that makes bio-ships notoriously difficult to finish off when crippled.
When a bio-ship reaches 0 Hull Integrity, it loses 2 points of speed, and suffers a -10 penalty to Manoeuvrability and Detection. In addition, it halves the strength of any Bio-plasma and Pyro-acid weapon symbiotes (rounding up), and loses the ability to use Feeder Tentacles, Massive Claws, Torpedoes or Launch Bays as it focuses all its efforts on staying alive.

Due to their biological nature, bio- ships also use a different Critical Hit chart to normal ships.

Roll – Result

1 – Pierced: A lucky hit has punched a hole in the creature‘s flank, exposing it to space.
The attacker selects a single Symbiote it knows about that is not the central nerve
cluster or the heart. Vast sphincters and fleshy valves shut off the area, preventing
any more loss of gas or fluid than has already occurred.
2 – Internal Injuries: The force of the hit cracks chitin plates and fractures bone,
damaging the organs beneath the surface. The attacker selects a single symbiote he
is aware of. This symbiote is wounded.
3 – Sensory Network Wounded: The bio-ship‘s senses are scrambled by the impact,
blinding it. Until the wound can be healed, all shooting tests have -30 to hit, and all
sensory tests to detect anything more than 1 VU away automatically fail.
4 – Discharge Vents Wounded: A number of the bio-ship‘s discharge vents are hit,
rendering them temporarily useless. Until the wound can be healed, it cannot move
or manoeuvre properly. Roll 1d10. On a 1-7, the bio-ship‘s manoeuvrability is
reduced by -20. On an 8-10, the bio-ship cannot turn.
5 – Serious Wound: A great rent is opened in the creature‘s flesh, leaking ichor into the
void. At the end of every strategic turn, roll a d100. If the roll is equal or less to the
bio-ship‘s remaining Hull Integrity, then the wound hasn‘t gotten any more severe.
If the roll is higher than the bio-ship‘s remaining Hull Integrity, it loses an
additional 1d5 Hull Integrity as the bleeding and tearing of the wound get worse.
This can be healed.
6 – Impellor Vanes crippled: The long vanes and tendrils which propel the ship
forward are snapped and mangled by the attack. Roll 1d10. On a 1-7, the bio-ship‘s
speed is halved. On an 8-10, the bio-ship‘s speed is reduced to 1. This can be healed.
7 – Spore Cysts ruptured: The bio-ship‘s Spore Cysts are smashed and mangled by the
attack, slaying the symbiotes that produce the spores and preventing them from
replenishing the bio-ship‘s spore cloud. The ship will no longer produce spores.
This injury cannot be repaired.
8 – Synapse Node ruptured: The bio-ship takes a particularly heavy blow which shreds
nerve fibres and tears the Synapse Node, causing it to cease functioning. The ship
cannot attempt to resist acting on instinctive behaviour until this injury is healed.
9-10 Severe Wound: A vast gash is torn in the bio-ship‘s hull, hundreds of metres long
and leaking vital fluids into the void. Randomly select 1d5 vital organs and/or
symbiotes. Roll 1d10 for every symbiote and vital organ affected. On a 1-5, it is
depressurised. On a 6-8 it is depressurised and wounded. On a 9 or 10, it is
destroyed.
11 Massive Haemorrhage: The armoured hide of the beast is rent open in numerous
places, rupturing transfer capillaries and exposing organs to the void. Sprays of volatile fluids jet outwards in all directions, with a 50% chance causing a single bio-
plasma hit on any vessel within 1VU (roll separately for each). Roll 1d10; on a 1-7,
the bio-ship becomes a drifting carcass. On an 8-9, there is a biological eruption, on
a 10, the creature‘s bio-plasma detonates.

Drifting Carcass
Catastrophic injury slays the beast and it thrashes about in its death throes, leaving
nothing behind but a festering corpse hundreds or even thousands of metres long.
Roll 1d10 for every vital organ and every symbiote. On a 1-2, it remains intact, but
will soon die with the rest of the bio-ship as its vital functions fail. On a 3-7, it is
wounded and bleeding, spilling foul liquids everywhere. On an 8-10, it was
destroyed, leaving nothing but ragged flesh, splintered bone and toxic effluent
behind. A few creatures may still remain in the bio-ship‘s spawning chambers,
emerging as their parent dies, to menace any creature that dares to set foot aboard
the carcass.

Biological Eruption
The bio-ship explodes messily, spraying viral slime and corrosive ichor in all
directions. All starships within 1d5 VU of the exploding carcass must make a Hard
(-20) Pilot (Spacecraft)+Manoeuvrability Test or be struck by massive shards of
bone, spumes of corrosive ichor and gobbets of acidic flesh. Treat this as 1d5 pyro-
acid battery hits doing 1d10+4 damage each, which void shields and armour will
protect against normally.

Bio-plasma Detonation
With a blinding flash, bio-plasma leaks into the main arteries and oxygen sacs,
igniting violently and obliterating the bio-ship‘s remains in a massive explosion,
casting energised bio-plasma in all directions. Any starship within 1d10 VU of the
exploding bio-ship must make a Hard (-20) Pilot (Spacecraft)+Manoeuvrability
Test or be struck by the bio-plasma, doing 1d10+4 damage that void shields and
armour will not protect against.

Species of Bio-Ship

The following are the main broad categories of Bio-ship species. It has been theorized that all are actually the same species, simply developed in different ways and at different stages of maturation, with “cruisers” being immature Hive Ships, and Vanguard Droneships being swift, fragile, swiftly-matured versions of the Escort Droneships that accompany the hive fleets.
As with many theories about the Tyranids, nobody knows for certain.

Vanguard Droneship

Equivalent Classification: Raider
Dimensions: between approx 0.8 and 1.7 km
long, 0.2 to 0.6 km abeam approx
Mass: between 4 and 7 megatons approx
Accel: approx 4.5 gravities max sustainable acceleration
Broods of Vanguard Droneships range far ahead of the main hive fleets, seeking worlds suitable for consumption and seeding them with smaller vanguard organisms like Lictors and genestealers, casting them downwards in clouds of spores they emit while in low orbit. They periodically return to their parent Hive Fleet, reconnecting to the Hive Mind and sharing what it has found, gathering new cargo from the spawning chambers of larger bio-ships, and departing once more. They are swifter than most Tyranid bio-ships, but comparatively fragile and lightly-armed.

Speed: 8 Manoeuvrability: +30 (75)
Detection: +40 (85) Armour: 14
Hull Integrity: 30 Spore Cysts: 1
Ballistic Skill: 45 Boarding Value: 75
Willpower: 30 Weapons Capacity: 1 Prow Symbiotes
Weapon Symbiotes: One of either Pyro-Acid Battery (Strength 2, Range 4, Damage 1d10+3) or Feeder Tentacles
(special). All a Vanguard Droneship‘sweapons fire or attack into the bio-ship‘s
forward arc.

Special Rules
Vanguard Brood Telepathy: The creature‘s psychic connection to the Hive Mind is sufficiently strong to act independently of the Hive Fleets, particularly in large numbers, and to relay
information to nearby bio-ships during battle. A Vanguard Droneship gains a +10 bonus to its Willpower characteristic for every additional vessel within its brood. Bio-ships of all kinds gain a +10 bonus to detect or hit any enemy vessel within 2 VU of one or more Vanguard Droneships.

Kraken

Equivalent Classification: Frigate
Dimensions: between approx 0.8 and 1.7 km long, 0.2 to 0.6 km abeam approx
Mass: between 4 and 7 megatons approx
Accel: approx 4.5 gravities max sustainable acceleration
Kraken are void-predators, perfectly adapted to hunt down space-faring prey over vast distances. Commonly found accompanying both Vanguard broods (where they will find prey to hunt whenever the Vanguard Droneships find a world for their Hive Fleet to consume) and full Hive
Fleets (where they lurk around the flanks of the Fleet to consume any who come near).
Their voracious appetite for orbital stations and transport ships is legendary, and broods
of Kraken have rendered systems indefensible as they cripple and devour defence ships without end. Kraken are extremely resilient creatures, and swift to recover from crippling injuries. Their prows are capped with all manner of horrific weaponry, from adamantium-hard ramming
beaks to acid-spraying maws and razor-sharp claws a kilometre long that can rip through a ship‘s hull.

Speed: 8 Manoeuvrability: +30 (75)
Detection: +20 (65) Armour: 22
Hull Integrity: 45 Spore Cysts: 0
Ballistic Skill: 55 Boarding Value: 75
Willpower: 25 Weapons Capacity: 1 Prow

Symbiotes
Weapon Symbiotes: Any one of the following: Pyro-Acid Battery (2x Strength 3, Range 4, Damage 1d10+3), Massive Claws (special), Torpedoes (boarding torpedoes only, Strength 2, Accuracy 55) or Feeder Tentacles (special).

All a Kraken‘s weapons fire or attack into the bio-ship‘s forward arc.

Special Rules

Brood Telepathy: The creature‘s psychic connection to the Hive Mind is sufficiently strong to act independently of the Hive Fleets, especially in large numbers.
A Kraken gains a +10 bonus to its Willpower characteristic for every additional vessel
within its brood.

Regenerative Capabilities: Kraken are incredibly resilient beasts, able to endure injuries that would cripple other bio-ships of a similar mass and recover from those that cripple them. Every turn, a Kraken may either regain 1d5 lost Hull Integrity or regain the use of a wounded Symbiote or Vital Organ if it can roll under twice its remaining Hull Integrity or less on a d100.

Escort Droneship

Equivalent Classification: Frigate
Dimensions: between approx 0.8 and 1.7 km long, 0.2 to 0.6 km abeam approx
Mass: between 4 and 7 megatons approx
Accel: approx 4.5 gravities max sustainable acceleration
Slow and cumbersome compared to most escort vessels, broods of Escort Droneships gather near the flanks of Hive Ships, acting as a last line of defence for these crucial organisms. Heavily-armed, they attack vessels threatening their charge in swarms, overwhelming them with numbers and firepower

Speed: 4 Manoeuvrability: +10 (55)
Detection: +20 (65) Armour: 18
Hull Integrity: 40 Spore Cysts: 1
Ballistic Skill: 55 Boarding Value: 75
Willpower: 15 Weapons Capacity: 1 Prow Symbiotes
Weapon Symbiotes: Any one of the following: Pyro-Acid Battery (Strength 4, Range 4, Damage 1d10+3), Feeder Tentacles (special), or Bio-Plasma Discharge (Strength 2, Range 2, Damage 1d10+2). All an Escort Droneship‘s weapons fire or attack into the bio-ship‘s forward arc.

Special Rules

Protective Instincts: When acting on instinct and no other conditions apply, Escort Droneships may choose to move towards the nearest Hive Ship.

Slow to Manoeuvre: Escort Droneships are not swift creatures, and can only turn up to 45 degrees, in spite of being Frigate-sized.

Cruiser

Equivalent Classification: Cruiser
Dimensions: between approx 3.5 and 5 km long, 1.2 to 2.6 km abeam approx
Mass: between 15 and 30 megatons approx
Accel: approx 2.5 gravities max sustainable acceleration
Tyranid Cruisers represent a mixture of overgrown and battle-scarred escort drones and immature hive ships. They are incredibly dangerous creatures, aggressive in the attack as they storm forwards to destroy any threat to the Hive Ships of their fleet. Not being relied upon as Synapse Creatures, they can attack without caution or thought of self-preservation, turning their
heavy armament upon enemies eagerly and viciously.
When not surging forth in a multi-million-tonne wave of flesh and bone, Cruisers are typically found close to Hive Ships; it is theorised that these creatures cannot sustain themselves alone, and are reliant on the larger bio-ships for nourishment in a manner akin to a child being fed by a parent. Whether this is true or not has yet to be observed, for any vessel which gets close enough to witness such a thing is soon torn apart by these massive void-dwelling predators.

Speed: 4 Manoeuvrability: +10 (55)
Detection: +10 (65) Armour: 20
Hull Integrity: 65 Spore Cysts: 3
Boarding Value: 75
Ballistic Skill: 55
Willpower: 15
Weapons Capacity: 1 Prow, 1 Thorax, 2 Abdomen

Symbiotes
Weapon Symbiotes: The Prow weapon symbiote may be one of the following: Pyro-acid Battery (2x Strength 4, Range 4, Damage 1d10+3), Feeder Tentacles (special), Massive Claws (special),
Torpedoes (boarding torpedoes only, Strength 4, Accuracy 55). Except for Pyro-acid batteries, a Cruiser‘s Prow weapon symbiote may fire or attack into the forward arc. Pyro-acid batteries may fire into any of the forward, port, or starboard arcs.
The Thorax weapon symbiote may be one of the following:
Feeder Tentacles (special), Massive Claws (special), or Torpedoes (boarding torpedoes only, Strength 4, Accuracy 55). A Cruiser‘s Thorax weapon symbiote may fire or attack into the forward arc.
The Abdomen weapon symbiotes may be chosen from the following list: Pyro-acid Battery (Strength 4, Range 4, Damage 1d10+3), Bio-Plasma Discharge (Strength 2 Range 2, Damage 1d10+2). A Cruiser‘s Abdomen weapon symbiotes may fire into the port and starboard arcs.

Hive Ship

Equivalent Classification: Battleship Dimensions: 5km long or more, 1.8 km or more abeam approx
Mass: 25+ megatons approx
Accel: approx 1.8 gravities max sustainable acceleration
Hive Ships are monstrous void-swimming leviathans found at the heart of every Hive Fleet. Variation between individuals is extensive, in both size and armament, but all are clad in thick armour plating and spotted with weapons symbiotes. Their vast size contains great spawning caverns capable of producing millions upon millions of lesser organisms, engineering new creatures and unleashing all manner of horrors upon a world. Every Tyranid creature, even if only indirectly, comes from a Hive Ship, from the spores and micro-organisms that rain down on
unsuspecting worlds, to the ravening monsters that tear through a tank‘s armoured hide as if it were paper, to the other bio-ships of its fleet.

Speed: 4 Manoeuvrability: +0 (60)
Detection: +30 (90) Armour: 21
Hull Integrity: 90 Spore Cysts: 4
Ballistic Skill: 60 Boarding Value: 80
Willpower: 90
Weapons Capacity: 1 Prow, 1 Thorax, 3 Abdomen

Symbiotes
Weapon Symbiotes: The Prow weapon symbiote may be one of the following: Pyro-acid Battery (2x Strength 4, Range 6, Damage 1d10+3), Feeder Tentacles and Massive Claws (special, one choice), Torpedoes (boarding torpedoes only, Strength 6, accuracy 60), Bio-Plasma Spines
(2x Strength 2, Range 2, Damage 1d10+2).
Except for Bio-Plasma Spines, a Hive Ship‘s Prow weapon symbiote may fire or attack into the forward arc. Bio-Plasma Spines may fire into any of the forward, port, or starboard arcs.
The Thorax weapon symbiote may be one of the following:
Pyro-acid Battery (2x Strength 4, Range 6, Damage 1d10+3, Forward arc), Launch Bay (Strength 2, accuracy 60, Port and Starboard arcs), Bio-Plasma Discharge (2x Strength 2, Range 2, Damage 1d10+2, Forward, Port and Starboard arcs).
The Abdomen weapon symbiotes may be chosen from the following list: Pyro-acid Battery (Strength 4, Range 6, Damage 1d10+3),Launch Bay (assault boats and fighters only, Strength 1, accuracy 60), Bio-Plasma Discharge (Strength 2, Range 2, Damage 1d10+2). A Hive Ship‘s Abdomen weapon symbiotes may fire into the port and starboard arcs.

Special Rules
Cumbersome: Hive Ships are so massive that their bulk hinders their ability to manoeuvre. Hive Ships may not perform the Come to New Heading action.
Synapse Creature: Hive Ships are the ultimate Synapse Creatures, their minds capable of projecting a psychic signal over tens of thousands of kilometres with enough clarity to direct whole swarms and fleets of lesser creatures. This signal is at its strongest within 5 VU, allowing any bio-ship within that distance to use the Hive Ship‘s Willpower instead of its own, and the Hive Ship will never revert to instinctive behaviour itself. This synapse control has no bearing upon Tyranid creatures on the surface of a nearby planet, even if that planet‘s surface is within range – lesser synapse creatures are required to boost the signal to influence the petty brood creatures waging the ground war below.

Weapon Symbiotes

Bio-Plasma
Just as lesser Tyranids can adapt to produce Bio-Plasma, so can bio-ships produce it. On such a massive scale, these great blasts of bio-plasma can tear holes in starship hulls, yet move slowly enough to completely bypass void shields and similar defences. This limits their range, but this is
of little concern to a bio-ship, which seeks to close the distance with its prey anyway.
Bio-plasma attacks are resolved in the same manner as lances, but because of their low velocity, they ignore void shields as well.

Feeder Tentacles
Many bio-ships have huge tentacles which they use to “feed” on planetary atmospheres, and which can be used to punch through the hull of a ship allowing the Tyranid organisms inside to assault the enemy. A bio-ship with Feeder Tentacles may use them to greatly enhance its success when attempting to board an enemy vessel, gaining a +20 bonus to its Boarding Value.

Massive Claws
Tyranid vessels are terrifying at close quarters. Not only are they packed with bio-engineered monstrosities created only to kill, but the ships themselves are often evolved with claws to rip open the armour of a target, or crushing mandibles that latch onto the bio-ship‘s prey and slowly tears through decks and gantries. To use its massive claws, a bio-ship must attempt to ram. If this is successful, it will attack with its claws instead of ramming normally.
Roll a d100. If the result is 70 or less, one claw has hit, dealing 1d10 damage ignoring armour and void shields. For every additional two degrees of success, then an additional claw has latched on (up to a maximum of two claws for one set of Massive Claws, or four claws for two sets of Massive Claws present on the ship), with each claw dealing 1d10 damage ignoring
armour and void shields. If 6 or more degrees of success are scored, then the target
vessel suffers a single Critical Hit as well. If two or more claws hit, the bio-ship will not
let go until either its prey is destroyed or it is. If both ships are approximately the same
size, neither can move, but if one or other of the ships is larger, it may continue to move
at half speed, dragging the other with it.
Both may continue to use their ranged weapons, though only at half strength.
Either ship may engage in a boarding action. In every subsequent turn, the claws squeeze more tightly, and roll to hit again. If a bio-ship is crippled, it may not use its Massive Claws, even against a ship it is already clamped onto, though it will not let go until its target is destroyed or it is.

Pyro-acid Batteries
These Tyranid weapons work by launching compact organic shells containing virulent toxins and pyrophoric corrosive substances, collectively referred to as ‗Pyro-acids‘ (though the name is not technically accurate, it‘s simple and descriptive enough to have stuck in Imperial Navy parlance,
much to the distaste of both the Adeptus Mechanicus and the Administratum who prefer to catalogue such things with more technical precision). These can cause considerable damage on impact, but it is the release of their ravening payloads into the confines of a ship that can prove the most deadly – spilling toxic fumes, foul diseases, burning fluids and corrosive slime through internal compartments and causing untold damage.
Pyro-acid battery fire is resolved in the same way as an ordinary ship‘s macrocannon battery. Any ship which is hit by pyro-acid weapons has a chance that they will continue to be eaten away by the deadly payload. Ships which suffer a critical hit from a pyro-acid weapon will suffer an
additional Fire critical result in addition to the normal critical result (it‘s not actually a fire, but the long-term effects are similar, both in terms of damage and the influence on crew morale).

Spores
Tyranid bio-ships do not have turrets or shields in the normal sense, but instead rely on emitting a constantly-replenished physical barrier of spore clouds. Every spore is contains myriad virii, acids, toxins and mutagens capable of eating through hull armour with startling speed. The combined presence of millions or billions of these spores (some of which are microscopic,
others of which are the size of men, Ogryns or even battle tanks) produces an ablative armour effect as they absorb weapons fire and ordnance directed at the bio-ship they surround.
At the start of any Strategic Turn, bio-ships are surrounded by a number of spore clouds equal to their Spore Cyst rating, specified in their characteristics. Spores are automatically replenished on a regular basis, in much the same manner as shields. Spores are not cumulative, and never exceed the Spore Cyst rating of the ship. If a bio-ship is crippled, its Spore Cyst rating is not affected, as they go into overdrive to try and protect their injured host creature.
Spore clouds reduce the number of hits suffered by incoming weapons fire in exactly the same manner as void shields, as described on pages 220 and 221 of the Rogue Trader rulebook. Further, the presence of spore clouds has exactly the same effect as the presence of turrets on a ship, with each spore cloud having the same effect as a single point of turret rating.

Evolutionary Adaptations

As with all Tyranids, bio-ships swiftly adapt to the conditions they face, replacing ineffective symbiote organisms with ones better adapted to deal with a new threat.
Additional development is common amongst all bio-ships, growing and changing as they fight and consume. The following adaptations represent, to a degree, this additional mutability.

Accelerated Healing
The creature has enhanced its ability to deal with injury, and is now able to endure injuries that would cripple other bio-ships of a similar mass and recover from those that cripple them. Every turn, a bio-ship with this adaptation may either regain 1d5 lost Hull Integrity or regain the use of a wounded Symbiote or Vital Organ if it can roll under twice its remaining Hull Integrity or less on a d100.

Additional Discharge Vents
The bio-ship has evolved a greater number of discharge vents, allowing it to turn more swiftly. The bio-ship increases its Manoeuvrability by +10.

Additional Spore Cysts
The bio-ship gains an additional Spore Cyst.

Adrenaline Sacs
The propulsion valves, constrictor muscles and impellor vanes that propel the ship have grown in size and strength and are now supplied by great sacs of adrenaline that allow them to be pushed even further. On any Strategic Turn in which the bio-ship does not turn, it may move an additional 1d5 VUs.

Drone Link
The bio-ship maintains close psychic contact with nearby Vanguard Droneships, allowing it to use their keen senses to target its weapons. When there is a Vanguard Droneship within 2 VUs, it gains a +10 bonus on all to-hit rolls for Pyro-acid batteries.

Psychic Scream
Hive Ships only. The Hive Ship‘s presence reverberates through the Warp, sliding into the minds of non-Tyranids nearby and instilling within them a visceral and unshakeable dread. All non-Tyranids within 2 VU of the Hive Ship suffer an additional -10 penalty to Willpower, and all morale losses while within that distance are doubled.

Reinforced Carapace
This upgrade may be taken more than once. The bio-ship‘s mass has increased, and with that growth, its carapace and endoskeleton are heavily reinforced. The bio-ship gains an additional 3 points of Hull Integrity.

Solar Vanes
Enhancing its ability to draw on solar radiation for limited sustenance, the bio-ship can afford to act more swiftly. Its speed increases by 1.

Tenacity
The creature‘s weapon symbiotes are stronger and more able to continue functioning even when the host bio-ship is placed under stress. The bio-ship‘s pyro-acid and bio-plasma weapon symbiotes do not suffer any penalty to hit when the bio-ship performs Evasive Manoeuvres or Come to New Heading actions.

Source: Unearthed Apocrypha: The Great Devourer