Jegantha, the Wellspring + Horde of Notions + Thermopod + Hammer of Purphoros

Jegantha, the Wellspring

Horde of Notions

Thermopod

Hammer of Purphoros

How it works

1. Activate Jegantha by tapping it, adding that cannot be spent to pay generic mana costs.
2. Activate Thermopod 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 loop relies on Jegantha, the Wellspring being repeatedly cast and sacrificed to generate a surplus of red mana through Thermopod. Because Jegantha's ability produces exactly five colored mana in the exact colors needed, it completely covers the activation cost for Horde of Notions to continuously pull Jegantha right back out of the graveyard. While Hammer of Purphoros is mentioned in the setup, the core engine effortlessly cycles Jegantha between the battlefield and the graveyard to fuel infinite death triggers and red mana.