Well, all it takes is to have multiple units selected (maybe multiple casters because I always have had some mages and priest in a stack) then cast a targetted spell (I've done it with wither, pillar of flames or that death II spell which causes disease, can't remember name; probably other such spell will work too) and *poof*. I'll try to post some savegame from the most recent version later today (can't do it right now).
Ps. BTW the spell can be casted many times and won't trigger the "already casted this turn" promotion.
Ps. BTW the spell can be casted many times and won't trigger the "already casted this turn" promotion.