Sin, Unending Cataclysm + Intruder Alarm + Phyrexian Altar + Arbor Adherent

Sin, Unending Cataclysm

Intruder Alarm

Phyrexian Altar

Arbor Adherent

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. When Sin enters, Intruder Alarm triggers, untapping all creatures.
4. Activate Arbor Adherent by tapping it, adding an amount of or equal to Sin's toughness.
5. Activate Phyrexian Altar by sacrificing Sin, adding G/U.
6. Choose to return Sin to the command zone from your graveyard.
7. When Sin dies, it triggers, putting its counters on Arbor Adherent.
8. Repeat.

This ingenious loop turns Sin, Unending Cataclysm into a self-replacing engine by leveraging its unique replacement effect to enter with a massive pile of +1/+1 counters harvested from your own permanents. When you sacrifice Sin to Phyrexian Altar for mana and send it back to the command zone, its death trigger dumps all those accumulated counters onto Arbor Adherent. That explosive growth directly supercharges Arbor Adherent's second tapping ability, allowing it to generate an immense surplus of colored mana. Meanwhile, Intruder Alarm notices Sin re-entering the battlefield from the command zone and untaps Arbor Adherent, resetting the entire cycle so you can cast Sin over and over again to generate infinite mana, death triggers, and storm count.