Primal Prayers, Aetherstorm Roc, and Cavern Harpy

Prerequisites

• Primal Prayers on the battlefield
• Aetherstorm Roc on the battlefield
• Cavern Harpy in hand
• You have at least or enough mana to cast Cavern Harpy

Steps

1. Cast Cavern Harpy by paying due to Primal Prayers, if able, or by paying its mana cost
2. When Cavern Harpy enters the battlefield, it and Aetherstorm Roc trigger
3. Resolve the Aetherstorm Roc trigger, causing you to get
4. Resolve the Cavern Harpy trigger, returning it from the battlefield to your hand
5. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite storm count