Toph, Greatest Earthbender + Power Depot + Crystalline Crawler + Phantom Train + Shang-Chi, Martial Mentor

Toph, Greatest Earthbender

Power Depot

Crystalline Crawler

Phantom Train

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 Phantom Train 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. Resolve the Phantom Train ability.
9. Activate Phantom Train by sacrificing Toph. Choose to return Toph from your graveyard to the command zone.
10. Activate Crystalline Crawler by removing a +1/+1 counter from it, adding R/G.
11. Repeat step 10 until you have enough mana to cast Toph.
12. Repeat from step 2.

This elegant loop centers on the dynamic synergy between Power Depot and Toph, Greatest Earthbender, turning the Depot into an animated land creature that can be repeatedly sacrificed and returned. Shang-Chi, Martial Mentor supercharges the engine by doubling every single +1/+1 counter placed throughout the process, rapidly escalating your resources. Meanwhile, Crystalline Crawler acts as the battery, converting those amplified counters into the exact colored mana needed to recast Toph alongside Phantom Train's sacrifice outlet.