Pitiless Plunderer + Heartless Summoning + Myr Retriever + Junk Diver

Pitiless Plunderer

Heartless Summoning

Myr Retriever

Junk Diver

How it works

1. Cast Myr Retriever by paying 0 due to Heartless Summoning.
2. Myr Retriever dies as a state-based action due to having 0 toughness, triggering itself and Pitiless Plunderer.
3. Resolve the Myr Retriever trigger, returning Junk Diver from your graveyard to your hand.
4. Resolve the Pitiless Plunderer trigger, creating a Treasure token.
5. Activate the Treasure by tapping and sacrificing it, adding 1.
6. Cast Junk Diver by paying 1 due to Heartless Summoning.
7. Junk Diver dies as a state-based action due to having 0 toughness, triggering itself and Pitiless Plunderer.
8. Resolve the Junk Diver trigger, returning Myr Retriever from your graveyard to your hand.
9. Resolve the Pitiless Plunderer trigger, creating a Treasure token.
10. Repeat.

This clever loop exploits the deadly state-based toughness reduction of Heartless Summoning to turn your graveyard into a revolving door of robotic recyclers. As Myr Retriever and Junk Diver repeatedly perish upon entering the battlefield with zero toughness, Pitiless Plunderer quietly cashes in each tragic demise for a shiny new Treasure token. Cracking that Treasure provides the exact mana needed to recast the alternative automaton, creating a self-sustaining engine of endless artifacts hitting the graveyard and returning one another safely to your hand.