Yahenni, Undying Partisan is a rare Legendary Creature — Aetherborn Vampire card from Double Masters 2022 (2X2), collector number 99. Current market price: $0.51 (foil $2.30), TCGplayer market prices via Scryfall.
Haste Whenever a creature an opponent controls dies, put a +1/+1 counter on Yahenni. Sacrifice another creature: Yahenni gains indestructible until end of turn.