During a game, it is possible for some units to be made prone. This could be because they were affected by a Stun grenade, falling through a Pitfall or by some other means. The units are knocked unconscious and are laying prone.
All units that are made prone, follow these rules:
- When a unit is Prone, it is placed faced down on the square, and it remains there until the Reset phase.
- While a unit is Prone, they cannot perform any actions but they will be affected as normal by hazardous effects, blasts from weapons and psychic effects.
- Marine units can auto-kill Tyranid units that are prone and within their CAZ for 1AP.
- Tyranid units will ignore Marines that are prone and consider the living a bigger threat.
- Prone units allow movement to other units (Marine units must spend an extra AP to pass) but no unit can end their turn on the same square.
- Prone units allow LOS.
- During the Reset phase, all current prone units roll 1D6 and recover on a 4+. A recovered unit is stood up and faced as the owning player chooses. If they fail the dice roll, then they remain prone until the next Reset phase, where they can roll again.
Space Hulk Codex 