Phelia, Exuberant Shepherd, Wormfang Manta, and Hushwing Gryff

Prerequisites

• Phelia, Exuberant Shepherd on the battlefield
• Wormfang Manta on the battlefield
• Hushwing Gryff on the battlefield
• Phelia does not have summoning sickness, and cannot be blocked and killed by an opponent

Steps

1. Declare Phelia as an attacker
2. Phelia triggers, exiling Wormfang Manta
3. When Wormfang Manta leaves the battlefield, its second ability triggers, causing you to take an extra turn after this one
4. At the beginning of your end step, Phelia triggers, returning Wormfang Manta from exile to the battlefield, and putting a +1/+1 counter on Phelia
5. Wormfang Manta's first ability does not trigger when it enters the battlefield due to Hushwing Gryff
6. Repeat each turn

Results

• Infinite turns