Toph, Greatest Earthbender + Power Depot + Crystalline Crawler + Ashnod's Altar + Shang-Chi, Martial Mentor

Toph, Greatest Earthbender

Power Depot

Crystalline Crawler

Ashnod's Altar

Shang-Chi, Martial Mentor

How it works

1. Play Power Depot, which will enter with a +1/+1 counter on it due to its modular ability
2. Cast Toph either from your hand or from the command zone by paying 2 plus commander tax if applicable.
3. When Toph enters, it triggers, earthbending Power Depot and putting a number of +1/+1 counters on Power Depot equal to the mana spent to cast Toph, increased by Shang-Chi.
4. Activate Ashnod's Altar by sacrificing Power Depot.
5. When Power Depot dies, its modular ability and Toph trigger.
6. Resolve the modular trigger, putting the +1/+1 counters that were on Power Depot onto Crystalline Crawler, increased by Shang-Chi.
7. Resolve the Toph trigger, returning Power Depot from your graveyard to the battlefield tapped. Power Depot will enter with a +1/+1 counter on it due to its modular ability
8. Activate Ashnod's Altar by sacrificing Toph. Choose to return Toph from your graveyard to the command zone.
9. Activate Crystalline Crawler by removing a +1/+1 counter from it, adding R/G.
10. Repeat step 9 until you have enough mana to cast Toph.
11. Repeat from step 2.

This ingenious loop turns Toph, Greatest Earthbender into a recursive engine by using her earthbend trigger to repeatedly resurrect Power Depot. Every time Power Depot returns, Ashnod's Altar converts it into raw mana while triggering its modular ability to seed counters elsewhere. The real magic of the setup relies on Shang-Chi, Martial Mentor, whose static replacement effect drastically amplifies all incoming +1/+1 counters. This ensures that Crystalline Crawler accumulates a massive surplus of counters to be filtered into colored mana, easily sustaining the loop and generating infinite resources for your board.