Unyielding Gatekeeper is a rare Creature — Elephant Cleric card from Murders at Karlov Manor Promos (PMKM), collector number 35p. Current market price: $0.34 (foil $0.89), TCGplayer market prices via Scryfall.
Disguise {1}{W} (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.) When this creature is turned face up, exile another target nonland permanent. If you controlled it, return it to the battlefield tapped. Otherwise, its controller creates a 2/2 white and blue Detective creature token.