Urge to Feed is a uncommon Instant card from Duel Decks: Sorin vs. Tibalt (DDK), collector number 22. Current market price: $0.19, TCGplayer market prices via Scryfall.
Target creature gets -3/-3 until end of turn. You may tap any number of untapped Vampire creatures you control. If you do, put a +1/+1 counter on each of those Vampires.