Sea Gate Colossus is a common Artifact Creature — Golem Warrior card from Zendikar Rising (ZNR), collector number 251. Current market price: $0.09 (foil $0.27), TCGplayer market prices via Scryfall.
This spell costs {1} less to cast for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)