Under the effect of this curse, enemy warriors who are mortally wounded are transformed into ghastly animated bodies and turn to attack their comrades.
Source: Warhammer Fantasy: 7th Edition
Betrayal in DeathURL Copied!
This spell can be cast on an enemy unit that is engaged in close combat and within 18" of the caster. If successfully cast, models who fall casualty will attack their own side in a final spasm of unholy energy. The spell lasts until the start of the caster's next turn. Fight the combat as normal. Any model in the affected unit which is killed during the combat immediately makes one further attack against a member of his own unit before it is removed - this is regardless of whether the model has already fought or not. Models killed by their own comrades will not be affected, only those killed by the enemy. The warrior will drop any weapon he's carrying and attack with his bare hands in a zombie-like fashion, thus the attack is always resolved at the model's basic Strength. In the case of mounted models, models riding chariots or monsters and so forth, only riders strike. If the dying model has a choice of different friendly models to attack, the Dark Emissary may choose which. Casualties caused by this spell will affect that round's combat resolution.