Trend angers.

Yeah, and the shock, surprise and frankly the embarrassment that a mighty vampire lord would experience when shitting himself makes him miss a turn, also he probably becomes more vulnerable. If not physically then definitely emotionally.

If I wrote a CRPG game, like an ASCII roguelike or something, I would totally include a spell that makes the target shit its pants. You could make that work, it would even be a useful thing in combat. Vampire lord misses a turn because he just shat his pants.