Clever Impersonator + Copy Enchantment + Oblivion Ring + Altar of the Brood Combo

Oblivion Ring and Altar of the Brood on the battlefield.

Clever Impersonator and Copy Enchantment in hand.

available

Cast Copy Enchantment by paying .

Copy Enchantment enters the battlefield, triggering Altar of the Brood and itself.

Resolve the Altar of Brood trigger, causing each opponent to mill a card.

Resolve the Copy Enchantment's trigger, becoming a copy of Oblivion Ring and exiling Oblivion Ring.

Cast Clever Impersonator by paying .

Clever Impersonator enters the battlefield, triggering Altar of the Brood and itself.

Resolve the Altar of Brood trigger, causing each opponent to mill a card.

Resolve the Clever Impersonator's trigger, becoming a copy of Copy Enchantment and exiling Copy Enchantment.

Copy Enchantment leaves the battlefield, returning Oblivion Ring from exile to the battlefield.

Altar of the Brood and Oblivion Ring triggers.

Resolve the Altar of Brood trigger, causing each opponent to mill a card.

Resolve the Oblivion Ring's trigger, exiling Clever Impersonator.

Clever Impersonator leaves the battlefield, returning Copy enchantment from exile to the battlefield.

Repeat from step 2.

Infinite creature ETB

Infinite creature LTB

Infinite mill