Boerzebul, Rakish Fiend

Whenever Boerzebul, Rakish Fiend attacks,
target opponent exiles an instant or sorcery card
from a graveyard. Until end of turn, you may
cast that spell, and you may spend mana as
though it were mana of any color to cast it
this way. If you don't, Boerzebul, Rakish Fiend
deals damage to each opponent equal to the
mana value of the card exiled this way.