Helbrute

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").