Fomori Vault is a mythic Land card from The Big Score (BIG), collector number 29. Current market price: $14.92 (foil $17.63), TCGplayer market prices via Scryfall.
{T}: Add {C}. {3}, {T}, Discard a card: Look at the top X cards of your library, where X is the number of artifacts you control. Put one of those cards into your hand and the rest on the bottom of your library in a random order.