Vren, the Relentless is a rare Legendary Creature — Rat Rogue card from Bloomburrow (BLB), collector number 239. Current market price: $0.48 (foil $0.66), TCGplayer market prices via Scryfall.
Ward {2} If a creature an opponent controls would die, exile it instead. At the beginning of each end step, create X 1/1 black Rat creature tokens with "This token gets +1/+1 for each other Rat you control," where X is the number of creatures that were exiled under your opponents' control this turn.