Annatar, Lord of the Gifts

{1}, Discard a card: Target opponent creates a
Ring of Power. Activate this ability only once
each turn. (It's an artifact token with
"{t}: Add {3} or two mana of any one color")
When Annatar, Lord of the Gifts leaves the battlefield, exile all Rings of Power.
{t}, {3}{b/r}: Transform Annatar.