Cemetery Prowler is a mythic Creature — Wolf card from Innistrad: Crimson Vow Promos (PVOW), collector number 191p. Current market price: $4.41 (foil $5.95), TCGplayer market prices via Scryfall.
Vigilance Whenever this creature enters or attacks, exile a card from a graveyard. Spells you cast cost {1} less to cast for each card type they share with cards exiled with this creature.