Crystalline Crawler, Dancing from Dark to Dawn, and Cavern Harpy

Prerequisites

• Crystalline Crawler on the battlefield
• Dancing from Dark to Dawn on the battlefield
• Cavern Harpy in hand
• available

Steps

1. Cast Cavern Harpy by paying its mana cost
2. Dancing from Dark to Dawn's first ability triggers, putting two +1/+1 counters on Crystalline Crawler
3. Resolve the Cavern Harpy spell
4. When it enters, it triggers, returning itself from the battlefield to your hand
5. Activate Crystalline Crawler twice by removing two +1/+1 counters from it, adding Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite storm count