Gwyn, Lord of Cinder

Persist
{x}{r}: Gwyn, Lord of Cinder gains +X/+0 until
the End Step. You may only activate the ability as
a sorcery. If this card is blocked and does not
destroy the creature blocking it, this card is
destroyed.
{2}{w}{w}, {t}, Sacrifice this card: Destroy all
creatures. They can't be regenerated. This ability
may only be activated as a sorcery, and only when
this card as a -1/-1 counter on it.