Vengeance of the Dead makes me angry!

[Belac]

I've never tried to cast the spell in game, but the literal reading of the manual suggests that it's an insta-death spell, MR saves ("The commander in that province who has killed the most units in combat has a chance of being killed in a nightmare by the souls of his victims. The target can escape by making a successful magic resistance roll"). What is the spell description in-game?