Eris, Fury of the Heavens

Flying, haste
Revenge — At the beginning of combat on your
turn, if you were dealt damage by a source an
opponent controls since the end of your previous
turn, you may pay {w}. If yo do, Eris attacks this
combat if able and you get an experience counter.
Creatures with flying you control get +1/+0 for
each experience counter you have.