Sin, Unending Cataclysm + Verdant Succession + Umbral Collar Zealot

Sin, Unending Cataclysm

Verdant Succession

Umbral Collar Zealot

How it works

1. Activate Umbral Collar Zealot 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 Umbral Collar Zealot ability.
6. Repeat.

This ingenious loop relies on the seamless interplay between Sin, Unending Cataclysm, Verdant Succession, and Umbral Collar Zealot. By feeding Sin into the Umbral Collar Zealot's sacrifice ability, you trigger Verdant Succession because Sin is a green nontoken creature, allowing you to immediately tutor another copy of Sin straight from your library onto the battlefield. As Sin goes to the graveyard, its death trigger also moves its accumulated +1/+1 counters onto another creature you control while shuffling itself back into your library, ensuring your supply never runs dry. This lets you cycle Sin endlessly to generate infinite sacrifice triggers, death triggers, leave-the-battlefield triggers, entry triggers, surveil value, and massive +1/+1 counters for the rest of your board.