Artorias, Abyss Walker

Lifelink, Flash
When Artorias enters play, sacrifice a creature
with a combined mana cost of {6} or more. If
a creature is sacrificed, this card gains +{x}/0. {x} is the number of creatures you control.
A once great knight reduced to a feral beast with
no desire but that to kill. He cares not for faction or allegiance.