Necropolis Fiend is a rare Creature — Demon card from Khans of Tarkir Promos (PKTK), collector number 82s. Current market price: — (foil $0.61), TCGplayer market prices via Scryfall.
Delve (Each card you exile from your graveyard while casting this spell pays for {1}.) Flying {X}, {T}, Exile X cards from your graveyard: Target creature gets -X/-X until end of turn.