Conclave Mentor is a uncommon Creature — Centaur Cleric card from March of the Machine Commander (MOC), collector number 320. Current market price: $0.77, TCGplayer market prices via Scryfall.
If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on that creature instead. When this creature dies, you gain life equal to its power.