Exchange of Words, Wormfang Manta, Opalescence, and Phelia, Exuberant Shepherd

Prerequisites

• Exchange of Words in hand
• Wormfang Manta on the battlefield
• Opalescence on the battlefield
• Phelia, Exuberant Shepherd on the battlefield
• available

Steps

1. Cast Exchange of Words by paying
2. When Exchange of Words enters, it triggers, exchanging the text boxes of itself and Wormfang Manta
3. Declare Phelia as an attacker, attacking a player that cannot kill it in combat
4. When Phelia attacks, it triggers, exiling and returning (at end step) Exchange of Words
5. When Exchange of Words leaves the battlefield, its ability from Wormfang Manta's textbox triggers, causing you to take an extra turn after this one
6. When Exchange of Words enters, it triggers, exchanging the text boxes of itself and Wormfang Manta
7. Repeat from step 3 each turn

Results

• Infinite turns
• Lock