Well, the frightfull explosion was an unstable transdimensional doorway.
Never cast fire unquenchable at lich fiends while jumping through a transdimensional doorway which happened to open up in front of the zombie hordes who were recently introduced to TV sports.
They get massively confused and wonder what the call was.
Especially when the dimensional gate goes unstable and goes all splodey everywhere.
I may still be picking lich bits out from behind my ears.
Hey! I taught you to wash behind your ears!