Dementor

Flying
Soul Drain-Dementor enters the field
tapped. At the beginning of your upkeep, the
opponent gains 1 soul drain counter. Once the
counter reaches 10, the opponent loses the
game.
Protection from everything except a Patronus
Charm
"If it can, the Dementor will feed on you long enough
to reduce you to something like itself...soulless and evil."
-Remus Lupin