Sin, Calamity Incarnate

At the beginning of each upkeep, create a 1/1 colorless Sinspawn creature token with flying.

Whenever you cast a spell from your graveyard or return a permanent to the battlefield from your graveyard, put a Despair counter on Sin.

Then if Sin has 6 or more Despair counters, transform it.
"You do not defeat Sin. You endure it—until it becomes you."