Sister White

Confess - Reveal this facedown evidence card.
Return target creature with mana value 3 or less
from your graveyard to the battlefield.
Flying, Skulk
Whenever a creature enters the battlefield under
an opponent's control, you may pay {2}. If you do,
put a +1/+1 counter Sister White.
Whenever a creature an opponent controls dies,
you may pay {2}. If you do, destroy target creature
with the same power or toughness as Sister
White.