Wormfang Manta, Erratic Portal, and Sundial of the Infinite

Prerequisites

• Wormfang Manta in hand
• Erratic Portal on the battlefield
• Sundial of the Infinite on the battlefield
• available

Steps

1. Cast Wormfang Manta by paying
2. Wormfang Manta enters the battlefield, triggering itself
3. In response, activate Erratic Portal by paying and tapping it, returning Wormfang Manta from the battlefield to your hand
4. When Wormfang Manta leaves the battlefield, it triggers, causing you to take an extra turn after this one
5. Activate Sundial of the Infinite by paying and tapping it, ending the turn and preventing Wormfang Manta's ETB ability from resolving
6. Repeat each turn

Results

• Infinite turns