Millennium Key

{T}: Add one mana of any color. {10}, {T}, Exile Millennium Key: You control target opponent during their next turn. This ability costs {1} less to activate for each other Millennium Item you control. Activate only as a sorcery. {I}(The other Millennium Items are Millennium Eye, Millennium Necklace, Millennium Puzzle, Millennium Ring, Millennium Rod, and Millennium Scale.)