Miliculus,

Other creatures can't attack.
At the beginning of your first precombat mainphase each turn, you may exile target creature. If you do, Miliculus, AEther-banned becomes a copy of that creature and gains this ability and, "Other creatures can't attack."
If Miliculus, AEther-banned would die, instead put a creature exiled with it onto the battlefield under its owner's control.