Jegantha, the Wellspring + Horde of Notions + Phyrexian Altar + Concordant Crossroads

Jegantha, the Wellspring

Horde of Notions

Phyrexian Altar

Concordant Crossroads

How it works

1. Activate Jegantha by tapping it, adding that cannot be spent to pay generic mana costs.
2. Activate Phyrexian Altar 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 looping engine relies on Horde of Notions acting as a recurring resurrection machine for Jegantha, the Wellspring, whose tap ability conveniently produces the exact five-color mana cost required to activate that graveyard-casting ability. Since Jegantha is an Elemental, it satisfies the Horde's targets while continuously feeding itself back into Phyrexian Altar for sacrifice, turning colored mana into a closed recycling loop. Meanwhile, Concordant Crossroads makes the whole thing instantly self-sustaining by granting haste to Jegantha the moment it enters the battlefield from the graveyard, allowing it to tap for mana again without waiting.