Vana, Nemesis Slayer

Flying, lifelink
Whenever a creature or planeswalker an
opponent controls activates an ability or deals
damage to you, you may pay life equal to twice its converted mana cost. If you do, destroy that
creature or planeswalker.
"We of The Flights have protected this plane for
thousands of years. We are beholden to no one, and no
power should be beyond our grasp."