This loop relies on the specialized color requirements of Jegantha, the Wellspring, whose tap ability produces exactly the five-color mana needed to fund Horde of Notions' recursion ability without leaving generic mana hanging. By channeling that mana into Horde of Notions, you pull Jegantha, the Wellspring straight out of the graveyard and back onto the battlefield for free. Tuktuk Rubblefort ensures the resurrected Jegantha instantly gains haste so it can tap again right away, while Phyrexian Altar acts as the sacrifice outlet that feeds the engine and refunds the exact colored mana you need to keep the cycle turning infinitely.