Aminatou, the Fateshifter + Spark Double + Altar of the Brood

Aminatou, the Fateshifter

Spark Double

Altar of the Brood

How it works

1. Activate Aminatou's second loyalty ability by removing a loyalty counter from it, blinking Spark Double.
2. Spark Double enters the battlefield as a non-legendary copy of Aminatou.
3. Altar of the Brood triggers, causing each opponent to mill one card.
4. Activate Spark Double's second loyalty ability by removing a loyalty counter from it, blinking Aminatou.
5. Aminatou enters the battlefield, triggering Altar of the Brood, causing each opponent to mill one card.
6. Repeat.