Conclave Tribunal is a uncommon Enchantment card from March of the Machine Commander (MOC), collector number 178. Current market price: $0.17, TCGplayer market prices via Scryfall.
Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) When this enchantment enters, exile target nonland permanent an opponent controls until this enchantment leaves the battlefield.