Necropolis Fiend is a rare Creature — Demon card from Khans of Tarkir (KTK), collector number 82. Current market price: $0.19 (foil $0.14), 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.