Inexorable Tide + Crystalline Crawler + Gemstone Array + Whitemane Lion

Inexorable Tide

Crystalline Crawler

Gemstone Array

Whitemane Lion

How it works

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

This clever loop relies on Inexorable Tide to act as a persistent engine, proliferating your board state every single time you cast a spell. While Whitemane Lion endlessly bounces itself back to your hand upon entering the battlefield to feed your cast count, Crystalline Crawler and Gemstone Array work together as a color-fixing battery; you spend the mana generated by removing their counters to recast the Lion, only to replenish those exact counters when Inexorable Tide triggers on the cast.