Jegantha, the Wellspring + Horde of Notions + Urabrask the Hidden + Yahenni, Undying Partisan

Jegantha, the Wellspring

Horde of Notions

Urabrask the Hidden

Yahenni, Undying Partisan

How it works

1. Activate Jegantha by tapping it, adding that cannot be spent to pay generic mana costs.
2. Activate Yahenni by sacrificing Jegantha.
3. Activate Horde of Notions by paying , causing you to cast Jegantha from your graveyard without paying its mana cost.
4. Repeat.

This clever loop turns the strict restriction on Jegantha, the Wellspring into a self-sustaining engine by tapping it for the exact WUBRG mana needed to fuel Horde of Notions. Because Horde of Notions allows you to cast that same Jegantha directly out of your graveyard, you can continually feed the cycle without ever paying actual mana costs. Meanwhile, Urabrask the Hidden ensures Jegantha enters the fray with immediate haste so it can be tapped right away, and Yahenni, Undying Partisan acts as both the sacrificial outlet to bin Jegantha and a growing threat that reaps endless death triggers along the way.