Vigilant of Alara

Exalted (Whenever a creature you control attacks
alone, that creature gets +1/+1 until end of turn.)
Cascade (When you cast this spell, exile cards from
the top of your library until you exile a nonland card
that costs less. You may cast it without paying its
mana cost. Put the exiled cards on the bottom of your library in a random order.)
{t}: Destroy target creature that dealt damage to
you this turn.