Leonardo, Sewer Samurai + Tatterkite + Ashnod's Altar + Stenn, Paranoid Partisan

Leonardo, Sewer Samurai

Tatterkite

Ashnod's Altar

Stenn, Paranoid Partisan

How it works

1. Cast Tatterkite from your graveyard by paying 2 due to Stenn. It won't enter with a finality counter on it due to its static ability.
2. Activate Ashnod's Altar by sacrificing Tatterkite, adding CC
3. Repeat.

This clever loop turns the graveyard into a tireless engine by leveraging Leonardo, Sewer Samurai's ability to let you cast 1-power or 1-toughness creatures from your graveyard. Tatterkite is the star of the show here, because its static ability prevents counters from being put on it, effectively bypassing the finality counter that Leonardo would normally force upon creatures cast from the graveyard. To make the loop economically viable, Stenn, Paranoid Partisan steps in as a cost reducer, shaving {1} off the cost of your artifact spells (by choosing artifact when it enters). Finally, Ashnod's Altar provides the muscle and the mana, letting you sacrifice Tatterkite for colorless energy and feeding the exact mana needed to recast it indefinitely.