Karlov of the Ghost Council is a mythic Legendary Creature — Spirit Advisor card from Ravnica Remastered (RVR), collector number 437. Current market price: $12.78 (foil $18.17), TCGplayer market prices via Scryfall.
Whenever you gain life, put two +1/+1 counters on Karlov. {W}{B}, Remove six +1/+1 counters from Karlov: Exile target creature.