Kavia, Essence Drinker

Whenever a creature you don't control dies or is countered, you may exile it. If you do, you may
put a +1/+1 counter on Kavia.
Whenever Kavia deals combat damage to a
player, exile that many cards from the top of
their library. Until end of turn, you may
cast those cards and you may spend mana as
though it were mana of any type to cast them.