Mirrodin Besieged + Myr Retriever + Scrap Trawler + Krark-Clan Ironworks

Mirrodin Besieged

Myr Retriever

Scrap Trawler

Krark-Clan Ironworks

How it works

1. Activate Krark-Clan Ironworks by sacrificing Scrap Trawler, adding CC.
2. When Scrap Trawler dies, it triggers, returning Myr Retriever from your graveyard to your hand.
3. Cast Myr Retriever by paying 2.
4. Mirrodin Besieged triggers, creating a 1/1 Myr artifact creature token.
5. Activate Krark-Clan Ironworks twice by sacrificing the Myr and Myr Retriever, adding CCCC.
6. When Myr Retriever dies, it triggers, returning Scrap Trawler from your graveyard to your hand.
7. Cast Scrap Trawler by paying 3.
8. Mirrodin Besieged triggers, creating a 1/1 Myr artifact creature token.
9. Repeat.

This loop turns the recycling bin of your graveyard into an endless engine of value, fueled by Krark-Clan Ironworks to generate infinite colorless mana. Scrap Trawler and Myr Retriever form a mutually recursive recovery loop when sacrificed, where each robot's death allows it to fish the other back out to hand. Meanwhile, Mirrodin Besieged watches the artifact-heavy proceedings to flood the board with an endless army of Myr tokens—or simply bides its time until its alternate win condition can close out the game.