Toph, Greatest Earthbender + Power Depot + Crystalline Crawler + Ashnod's Altar + Loading Zone

Toph, Greatest Earthbender

Power Depot

Crystalline Crawler

Ashnod's Altar

Loading Zone

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 Loading Zone.
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 Loading Zone.
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 brilliant loop turns the modular ability of Power Depot and the counter-doubling effect of Loading Zone into an endless engine of sacrifice and resurrection. When Toph, Greatest Earthbender enters the battlefield, she earthbends Power Depot back to life while leveraging her massive mana value to flood the land with counters. Ashnod's Altar converts your expendable assets into colorless mana, while Crystalline Crawler acts as a versatile battery, stockpiling the staggering number of counters generated by Loading Zone and cracking them for whatever colored mana you need to recast your commander.