Spider-Man India + Crystalline Crawler + Umori, the Collector + Whitemane Lion

Spider-Man India

Crystalline Crawler

Umori, the Collector

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 elegant loop centers on casting Whitemane Lion for a single white mana, which is discounted all the way down thanks to Umori, the Collector naming creatures as its chosen type. As Whitemane Lion enters the battlefield, its own trigger forces you to bounce it right back to your hand, but this also triggers Spider-Man India to permanently grow your board by dropping a +1/+1 counter onto Crystalline Crawler. You then cash in that very same counter using Crystalline Crawler's mana ability to generate the exact white mana needed to recast Whitemane Lion all over again.