Inexorable Tide, Crystalline Crawler, Pentad Prism, and Cavern Harpy

Prerequisites

• Inexorable Tide on the battlefield
• Crystalline Crawler on the battlefield
• Pentad Prism on the battlefield
• Cavern Harpy in hand
• Crystalline Crawler has at least one +1/+1 counter on it
• Pentad Prism has at least one charge counter on it
• available

Steps

1. Cast Cavern Harpy by paying
2. Inexorable Tide triggers, putting a +1/+1 counter on Crystalline Crawler and a charge counter on Pentad Prism
3. When Cavern Harpy enters the battlefield, it triggers, returning itself from the battlefield to your hand
4. Activate Pentad Prism by removing a charge counter from it, adding
5. Activate Crystalline Crawler's first ability by removing a +1/+1 counter from it, adding
6. Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite proliferate
• Infinite storm count