Jegantha, the Wellspring + Horde of Notions + Viscera Seer + Tuktuk Rubblefort

Jegantha, the Wellspring

Horde of Notions

Viscera Seer

Tuktuk Rubblefort

How it works

1. Activate Jegantha by tapping it, adding that cannot be spent to pay generic mana costs.
2. Activate Viscera Seer 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 infinite loop centers on Jegantha, the Wellspring, whose activated ability conveniently produces the exact five-color mana requirement—{W}{U}{B}{R}{G}—needed to fuel Horde of Notions' ability, bypassing the restriction that Jegantha's mana can't pay generic costs. To get Jegantha back into the graveyard to be recast, you sacrifice it to Viscera Seer, which also rewards your endless cycle with infinite scry 1 triggers. Finally, Tuktuk Rubblefort's passive ability grants your creatures haste, ensuring Jegantha can be activated the moment it returns to the battlefield without suffering from summoning sickness.