Gwyn, Lord of Cinder

When Gwyn, Lord of Cinder is transformed faced up, deal three damage to all creatures
and then give all creatures undying as long as Gwyn, Lord of Cinder is on the battlefield.
Whenever a creature dies, give Gwyn, Lord
of Cinder a +1/+1 counter.
He runs himself hollow and burns all his knights alive. A shadow of his former self. They lock him away, far beneath his crumbling shrine.