Clever Impersonator, Estrid's Invocation, Oblivion Ring, and Sage of Mysteries

Prerequisites

• Clever Impersonator in hand
• Estrid's Invocation in hand
• Oblivion Ring on the battlefield
• Sage of Mysteries on the battlefield
• available

Steps

1. Cast Estrid's Invocation by paying
2. Estrid's Invocation enters the battlefield, triggering Sage of Mysteries and itself
3. Resolve the Altar of Brood trigger, causing each opponent to mill a card
4. Resolve the Estrid's Invocation's trigger, becoming a copy of Oblivion Ring and exiling Oblivion Ring
5. Cast Clever Impersonator by paying
6. Clever Impersonator enters the battlefield, triggering Sage of Mysteries and itself
7. Resolve the Altar of Brood trigger, causing each opponent to mill a card
8. Resolve the Clever Impersonator's trigger, becoming a copy of Estrid's Invocation and exiling Estrid's Invocation
9. Estrid's Invocation leaves the battlefield, returning Oblivion Ring from exile to the battlefield
10. Sage of Mysteries and Oblivion Ring triggers
11. Resolve the Altar of Brood trigger, causing each opponent to mill a card
12. Resolve the Oblivion Ring's trigger, exiling Clever Impersonator
13. Clever Impersonator leaves the battlefield, returning Estrid's Invocation from exile to the battlefield
14. Repeat from step 2

Results

• Infinite ETB
• Infinite LTB
• Infinite mill