Toph, Greatest Earthbender + Power Depot + Crystalline Crawler + Phyrexian Altar + Doc Samson, Super Psychiatrist

Toph, Greatest Earthbender

Power Depot

Crystalline Crawler

Phyrexian Altar

Doc Samson, Super Psychiatrist

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 Doc Samson.
4. Activate Phyrexian 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 Doc Samson.
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 Phyrexian 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 intricate loop uses Phyrexian Altar as a reliable sacrifice outlet to continually recycle both Power Depot and Toph, Greatest Earthbender through your graveyard. As Toph repeatedly reanimates Power Depot and Doc Samson aggressively amplifies every single counter placed onto Crystalline Crawler, you stockpile a mountain of +1/+1 counters. You can then peel those counters right back off Crystalline Crawler to generate all the colored mana you need to recast Toph and repeat the whole cycle infinitely.