Sin, Unending Cataclysm is a rare Legendary Creature — Leviathan Avatar card from Final Fantasy Commander (FIC), collector number 95. Current market price: $0.26, TCGplayer market prices via Scryfall.
Flying, trample As Sin enters, remove all counters from any number of artifacts, creatures, and enchantments. Sin enters with X +1/+1 counters on it, where X is twice the number of counters removed this way. When Sin dies, put its counters on target creature you control, then shuffle this card into its owner's library.