Forgotten Gateway

At the beginning of each of your main phases,
each other player adds {c}. This mana doesn't
empty as steps and phases end.
{3}, Exile another permanent you control: Target player other than you and Forgotten Gateway's
owner gains control of it. At the beginning of
that player's next main phase, return all
permanents you exiled this way to the battlefield
under their owner's control. Activate as a sorcery.