Agatha's Soul Cauldron, Myojin of Towering Might, Tekuthal, Inquiry Dominus, and Workhorse

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Myojin of Towering Might in exile
• Tekuthal, Inquiry Dominus on the battlefield
• Workhorse on the battlefield

Steps

1. Activate Tekuthal using Myojin of Towering Might's ability by removing an indestructible counter from it, putting six +1/+1 counters on Workhorse, and two +1/+1 counters on any creature you control
2. Activate Workhorse three times by removing three +1/+1 counters from it, adding
3. Activate Tekuthal by paying and removing three +1/+1 counters from Workhorse, putting an indestructible counter on it
4. Repeat

Results

• Infinite +1/+1 counters
• Infinite colored mana that can only be spent to activate abilities of creatures you control
• Infinite colorless mana