Hoverguard Sweepers + Morophon, the Boundless + Leyline of Mutation

Hoverguard Sweepers

Morophon, the Boundless

Leyline of Mutation

How it works

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

This elegant loop relies on Leyline of Mutation to bypass the traditional mana cost of spells, letting you cast them for just {W}{U}{B}{R}{G}. Morophon, the Boundless steps in to reduce that colored cost by {W}{U}{B}{R}{G}, effectively making your spells free to cast. With the mana requirement entirely eliminated, you can endlessly cast Hoverguard Sweepers for zero mana; its own enters-the-battlefield trigger then forces it straight back to your hand so you can repeat the process indefinitely.