Combat Celebrant [Amonkhet Prerelease Promos] Arena League 1999 {T}: Add one mana of

{T}: Add one mana of any color

brought on by the search for the Immortal Sun

but I didn't expect it from the building itself

Creatures and nonbasic lands your opponents control enter the battlefield tapped

or Dragon creature card from your hand onto the battlefield tapped and attacking that opponent

Combat Celebrant [Amonkhet Prerelease Promos] Arena League 1999 {T}: Add one mana ofSet: Amonkhet Prerelease Promos Type: Creature Human Warrior Rarity: Mythic Cost: {2}{R} If Combat Celebrant hasn't been exerted this turn, you may exert it as it attacks. When you do, untap all other creatures you control and after this phase, there is an additional combat phase. (An exerted creature won't untap during your next untap step.)