Jegantha, the Wellspring + Horde of Notions + Urabrask the Hidden + Phantom Train

Jegantha, the Wellspring

Horde of Notions

Urabrask the Hidden

Phantom Train

How it works

1. Activate Jegantha by tapping it, adding that cannot be spent to pay generic mana costs.
2. Activate Phantom Train 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 uses Horde of Notions as the engine, leveraging its ability to cast Elementals directly from the graveyard without paying their mana costs. Jegantha, the Wellspring pulls double duty here: first by tapping to generate the exact five-color mana required to pay Horde of Notions' activation cost, and then by acting as the repeatable target that gets sacrificed to Phantom Train. Phantom Train not only absorbs Jegantha into the graveyard while growing larger with +1/+1 counters, but also turns itself into a creature so you can keep sacrificing things to it. Finally, Urabrask the Hidden ensures that Jegantha enters the battlefield with haste each time it loops back, allowing it to tap immediately for mana and keep the cycle running endlessly.