Leonardo, Sewer Samurai + Tatterkite + Ravenous Intruder + Ezzaroot Channeler

Leonardo, Sewer Samurai

Tatterkite

Ravenous Intruder

Ezzaroot Channeler

How it works

1. Cast Tatterkite from your graveyard by paying 0 due to Ezzaroot Channeler. It won't enter with a finality counter on it due to its static ability.
2. Activate Ravenous Intruder by sacrificing Tatterkite.
3. Repeat.

This clever engine revolves around casting Tatterkite for free from your graveyard, a feat made possible because Ezzaroot Channeler's tap ability provides enough life-gain discount to reduce Tatterkite's mana cost to zero. Normally, Leonardo, Sewer Samurai would saddle that graveyard-cast creature with a finality counter upon entry, but Tatterkite's own static ability steps in to prevent any counters from being placed on it at all. Once it safely enters the battlefield, you feed it directly to Ravenous Intruder to sacrifice it as an artifact, sending it straight back to the graveyard so the loop can begin anew.