Here's my Daemonic Possessions for BFG!
First, some basic rules that appy to all Daemonic Possessions. Fisrt, the ship must have a Chaos Warmaster or Lord with an appropriate Mark of Chaos for the possession they are taking. Second, Daemoniccally Possessed ships have no crew. The only crew onboard are the Lord and perhaps a small cabal of acolytes. The ship is crewed by an enourmouse daemonic entity. As such, enemy ships may not initaite boarding actions or make hit and run attacks against these ships(it should be noted that subplots requiring boarding an enemy vessel may not make these ships their goal). Also, Daemonically possessed ships may not initiate boarding actions, make teleport attacks, or use Assault Shuttles or Boarding Torpedoes. Daemonically possessed ships are always assumed to use the leadership of the Lord or Warmaster crewing the ship, and Daemonically Possessed ships may not be used in squadrons with non-possessed ships or ships possessed by another Chaos Power. No ship may possess two different daemonic possessions.
A ship possessed by a Destroyer of Khorne has all manner of destructive blades and spikes covering the ship, especially concentrated in the prow. When a Destroyer of Khorne makes a ramming attack, it doubles it's number of starting hits for purposes of number of dice rolled for damage. This is also applied to enemy ships attampting to ram the Destroyer as the enemy ship impales itself on the spikes and blades. Also, the ship is assumed to automatically pass the leadership test required to ram an enemy ship.
A ship with the Warp Flame is constantly surrounded by swirling flames. This has an effect of doubling it's turret value as the flames consume incoming enemy ordnace. Also, the ship always counts as shielded for purposes of blast markers, celestial phenomena, etc., even if its shields collapse. So it cannot be damaged by moving through blast markers or dust clouds.
A ship equipped with a warp amp concentrates psychic warp energy and then releases it in an uncontrolled blast, sending shockwaves of energy out from the ship. In any shooting phase, the Warp Amp may create a blast that is the same as a Plasma Drive Overload on the Catastrophic Damage table. Every ship within 3d6 cm of the ship is struck by lance shots equal to half the starting Damage capacity of the ship. The ship itself is unaffected by this.
A ship with the cloud is surrounded by a sickly green cloud at all times. This ship counts as though it is surrounded by a gas cloud. The size of the cloud is determined at the start of the game. It is D6x2cm wide by D6x5cm long. This is centered on the ship with the long way aligned with the keel. The cloud moves with the ship. The gas cloud damages and slows unshielded ships, and effect firing of other ships as normal. But the infected ship itself is not harmed or slowed by this cloud if it loses it's shields, nor does it's shooting suffer from shooting through it.
The cost for daemonically possessing a ship is increasing the ships cost by 20%(do this first, then campaign upgrades).