Sin, Unending Cataclysm + Verdant Succession + Phantom Train

Sin, Unending Cataclysm

Verdant Succession

Phantom Train

How it works

1. Activate Phantom Train 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 Phantom Train ability.
6. Repeat.

This loop turns the cyclical destruction of Sin, Unending Cataclysm into an engine of perpetual growth and rebirth, legal in formats like Commander and Legacy. By using Phantom Train's activated ability to sacrifice Sin, you trigger its death ability to recycle its counters onto another creature while shuffling Sin safely back into your library. Simultaneously, Verdant Succession catches the dying green creature and immediately plucks another copy of Sin right back out of your library onto the battlefield, setting you up to repeat the entire process indefinitely.