Sin, Unending Cataclysm + Thornbite Staff + Altar of Dementia + Selvala, Heart of the Wilds

Sin, Unending Cataclysm

Thornbite Staff

Altar of Dementia

Selvala, Heart of the Wilds

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 Selvala by paying and tapping it, adding at least plus an additional X equal to Sin's power minus 3.
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 and Selvala trigger.
7. Resolve the Sin trigger, putting its counters on Selvala.
8. Resolve the Selvala trigger, untapping it.
9. Resolve the Altar of Dementia ability.
10. Repeat.

This loop transforms Sin, Unending Cataclysm into a repeatable ballistic missile by leveraging its massive entry-size and death trigger. When equipped with Thornbite Staff, Sin gains both a direct damage tap ability and an untap trigger whenever a creature dies, though here we bypass the damage to feed Altar of Dementia directly. By sacrificing the cataclysmic beast to Altar of Dementia, you mill your opponents while fueling Selvala, Heart of the Wilds—whose mana generation scales dynamically with the enormous +1/+1 counters Sin accumulates as it enters and passes along—to pay the commander tax for endless recasts.