Gandalf the White + Scrap Trawler + Myr Retriever + Krark-Clan Ironworks

Gandalf the White

Scrap Trawler

Myr Retriever

Krark-Clan Ironworks

How it works

1. Activate Krark-Clan Ironworks twice by sacrificing the nontoken artifact with mana value one or less and Myr Retriever, adding CCCC.
2. When Myr Retriever dies, its ability triggers twice, returning Scrap Trawler and the nontoken artifact with mana one or less to your hand from your graveyard.
3. Cast Scrap Trawler and the nontoken artifact by paying at most 4.
4. Activate Krark-Clan Ironworks twice by sacrificing the nontoken artifact and Scrap Trawler, adding CCCC.
5. Scrap Trawler triggers twice for itself dying, and twice for the nontoken artifact.
6. Resolve the Scrap Trawler triggers for the nontoken artifact, returning any applicable artifact to your hand from your graveyard.
7. Resolve the remaining Scrap Trawler triggers, returning the nontoken artifact and Myr Retriever to your hand from your graveyard.
8. Cast the nontoken artifact and Myr Retriever by paying at most 3.
9. Repeat.