Necron Monolith is a rare Artifact — Vehicle card from Warhammer 40,000 Commander (40K), collector number 161. Current market price: $0.95, TCGplayer market prices via Scryfall.
Flying, indestructible Eternity Gate — Whenever this Vehicle attacks, mill three cards. For each creature card milled this way, create a 2/2 black Necron Warrior artifact creature token. Crew 4 (Tap any number of creatures you control with total power 4 or more: This Vehicle becomes an artifact creature until end of turn.)