Sonic the Werehog

Trample, menace, reach.
Whenever Sonic the Werehog deals combat damage
to a player, you may pay {x} life equal to the amount
of damage dealt to that player. If you do, you may
cast a card with mana value {x} or less from your
hand or graveyard without paying its mana cost. If
that card would be put into the graveyard from anywhere, exile it instead.
Nightbound.