Cephalid Coliseum is a mythic Land card from From the Vault: Realms (V12), collector number 3. Current market price: — (foil $11.07), TCGplayer market prices via Scryfall.
{T}: Add {U}. This land deals 1 damage to you. Threshold — {U}, {T}, Sacrifice this land: Target player draws three cards, then discards three cards. Activate only if there are seven or more cards in your graveyard.