Blood Researcher is a common Creature — Vampire Druid card from Strixhaven: School of Mages (STX), collector number 166. Current market price: $0.17 (foil $0.18), TCGplayer market prices via Scryfall.
Menace (This creature can't be blocked except by two or more creatures.) Whenever you gain life, put a +1/+1 counter on this creature.