Sin, Unending Cataclysm + Thornbite Staff + Phyrexian Altar + Heronblade Elite

Sin, Unending Cataclysm

Thornbite Staff

Phyrexian Altar

Heronblade Elite

How it works

1. Cast Sin either from your hand or command zone by paying 5 plus commander tax if applicable.
2. As Sin enters, remove all counters from all artifacts, enchantments and creatures you control, putting twice that many +1/+1 counters on Sin.
3. Activate Phyrexian Altar by sacrificing Sin, adding G/U.
4. Choose to return Sin to the command zone from your graveyard.
5. When Sin dies, it and Heronblade Elite trigger.
6. Resolve the Sin trigger, putting its counters on Heronblade Elite.
7. Resolve the Heronblade Elite trigger, untapping it.
8. Activate Heronblade Elite by tapping it, adding an amount of or equal to its power.
9. Repeat.

This loop relies on recycling Sin, Unending Cataclysm directly from the command zone while channeling its massive counter-scaling into Heronblade Elite, which is equipped with Thornbite Staff. Every time Sin enters the battlefield, it feasts on existing counters to grow enormous before you sacrifice it to Phyrexian Altar for mana and send it back to command the zone. Its death triggers then pump Heronblade Elite with those counters, while Thornbite Staff uses the creature death to instantly untap the Elite. This lets you tap Heronblade Elite for a flood of colored mana to recast Sin, repeating the cycle for infinite mana, triggers, and an infinitely growing human champion.