Sin, Unending Cataclysm + Verdant Succession + Grimgrin, Corpse-Born

Sin, Unending Cataclysm

Verdant Succession

Grimgrin, Corpse-Born

How it works

1. Activate Grimgrin by sacrificing Sin.
2. When Sin dies, it and Verdant Succession trigger.
3. Resolve the Sin trigger, moving any counters from it onto another creature you control, and then shuffling Sin into your library.
4. Resolve the Verdant Succession trigger, searching your library for Sin and putting it onto the battlefield.
5. Resolve the Grimgrin ability.
6. Repeat.