Wormfang Manta, Aminatou, the Fateshifter, Spark Double, and Karn, Argent Defender

Prerequisites

• Wormfang Manta on the battlefield
• Aminatou, the Fateshifter on the battlefield
• Spark Double on the battlefield
• Karn, Argent Defender on the battlefield

Steps

1. Activate Aminatou's second loyalty ability by removing a loyalty counter from it, blinking Wormfang Manta
2. When Wormfang Manta leaves the battlefield, its second ability triggers, causing you to take an extra turn after this one
3. Wormfang Manta entering does not cause its abillity to trigger due to Karn
4. Activate Spark Double's second loyalty ability by removing a loyalty counter from it, blinking Aminatou
5. Activate Aminatou's second loyalty ability by removing a loyalty counter from it, blinking Spark Double
6. Choose to have Spark Double enter as a copy of Aminatou that isn't legendary
7. Wormfang Manta
8. Repeat each turn

Results

• Infinite turns
• Lock