Morophon, the Boundless + Jodah, Archmage Eternal + Whitemane Lion

Morophon, the Boundless

Jodah, Archmage Eternal

Whitemane Lion

How it works

1. Cast Whitemane Lion by paying 0.
2. When Whitemane Lion enters, it triggers, returning itself from the battlefield to your hand.
3. Repeat.

This clever loop achieves infinite creature enters-the-battlefield and leaves-the-battlefield triggers, along with an infinite storm count, by leaning entirely on cost reduction and alternative casting methods. Jodah, Archmage Eternal lets you bypass normal mana costs by paying a flat five-color requirement of {W}{U}{B}{R}{G}, while Morophon, the Boundless steps in as the engine's core by naming "Cat" (or any creature type) to reduce that exact color requirement by {W}{U}{B}{R}{G}, making your chosen spells completely free to cast. With the mana cost reduced to zero, you can repeatedly cast Whitemane Lion for free, whose own triggered ability forces it to immediately bounce itself back to your hand so you can cast it all over again.