Spider-Man India + Crystalline Crawler + Pearl Medallion + Whitemane Lion

Spider-Man India

Crystalline Crawler

Pearl Medallion

Whitemane Lion

How it works

1. Cast Whitemane Lion by paying .
2. Spider-Man India triggers, putting a +1/+1 counter on Crystalline Crawler.
3. When Whitemane Lion enters, it triggers, returning itself from the battlefield to your hand.
4. Activate Crystalline Crawler by removing a +1/+1 counter from it, adding .
5. Repeat.

This clever loop relies on Pearl Medallion reducing the cost of Whitemane Lion down to a single white mana, which can be entirely paid for by stripping a counter off Crystalline Crawler. When the Lion enters the battlefield, its own ability forces it right back to your hand, while simultaneously triggering Spider-Man India to place a fresh +1/+1 counter back onto Crystalline Crawler to replace the one you just spent. Because Spider-Man India lets you cast the Lion repeatedly without ever running out of mana or targets, you easily generate an endless cycle of creature enters-the-battlefield and leaves-the-battlefield triggers along with an infinite storm count.