Vashtorr the Arkifane

If your Army Faction is HERETIC ASTARTES, each time a unit with this ability is selected to shoot or fight, it can make a Dark Pact. If it does, it must first take a Leadership test before any effects of the Dark Pact are resolved; if that test is failed, that unit suffers D3 mortal wounds. Then, select one of the following abilities for that unit’s weapons to gain until the end of the phase:
■ [LETHAL HITS]
■ [SUSTAINED HITS 1]

Some models have 'Deadly Demise x' listed in their abilities. When such a model is destroyed, roll one D6 before removing it from play (if such a model is a TRANSPORT, roll before any embarked models disembark). On a 6, each unit within 6" of that model suffers a number of mortal wounds denoted by 'x' (if this is a random number, roll separately for each unit within 6").

During the Declare Battle Formations step, if every model in a unit has this ability, you can set it up in Reserves instead of setting it up on the battlefield. If you do, in the Reinforcements step of one of your Movement phases you can set up this unit anywhere on the battlefield that is more than 9" horizontally away from all enemy models.

If a unit with the Deep Strike ability arrives from Strategic Reserves, the controlling player can choose for that unit to be set up either using the rules for Strategic Reserves or using the Deep Strike ability.