Sin, Unending Cataclysm + Intruder Alarm + Altar of Dementia + Heronblade Elite

Sin, Unending Cataclysm

Intruder Alarm

Altar of Dementia

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. When Sin enters, Intruder Alarm triggers, untapping all creatures.
4. Activate Altar of Dementia by sacrificing Sin.
5. Choose to return Sin to the command zone from your graveyard.
6. When Sin dies, it triggers, putting its counters on Heronblade Elite.
7. Resolve the Altar of Dementia ability.
8. Activate Heronblade Elite by tapping it, adding an amount of or equal to its power.
9. Repeat.

This fascinating loop turns Sin, Unending Cataclysm into a recycling engine of cosmic scale, leveraging its massive entrance to fuel Heronblade Elite. Every time Sin enters the battlefield, it feasts on the counters around you to grow huge, while Intruder Alarm immediately untaps your entire board in response. This leaves Heronblade Elite ready to tap for a tidal wave of mana proportional to its monstrous power, while Altar of Dementia happily grinds your opponents' libraries to dust by sacrificing Sin over and over. By sending Sin back to the command zone upon death to recast it anew, you ensure that Heronblade Elite continually stacks up more counters and generates infinite colored mana, milling the table out entirely.