Krark-Clan Ironworks + Scrap Trawler + Myr Retriever + Chromatic Star + Mox Opal

Krark-Clan Ironworks

Scrap Trawler

Myr Retriever

Chromatic Star

Mox Opal

How it works

1. Announce the activation of Chromatic Star's ability, allowing you to activate mana abilities while delaying any triggered abilities until this ability has finished resolving.
2. Activate Mox Opal's mana ability by tapping it, adding one mana of any color.
3. Activate Krark-Clan Ironworks three times by sacrificing Mox Opal, Myr Retriever, and Krark-Clan Ironworks, adding six colorless mana.
4. Complete the activation of Chromatic Star by paying 1, tapping it, and sacrificing it, adding one mana of any color.
5. When the artifacts go to the graveyard in steps 3 and 4, Myr Retriever triggers once, Scrap Trawler triggers four times, and Chromatic Star triggers once.
6. Resolve Chromatic Star's triggered ability, drawing a card.
7. Resolve Myr Retriever's triggered ability, returning Krark-Clan Ironworks from your graveyard to your hand.
8. Resolve Scrap Trawler's triggered ability from Krark-Clan Ironworks, returning Myr Retriever from your graveyard to your hand.
9. Resolve Scrap Trawler's triggered ability from Myr Retriever, returning Chromatic Star from your graveyard to your hand.
10. Resolve Scrap Trawler's triggered ability from Chromatic Star, returning Mox Opal from your graveyard to your hand.
11. The final Scrap Trawler triggered ability from Mox Opal fails to resolve due to lack of targets.
12. Cast Krak-Clan Ironworks, Myr Retriver, Chromatic Star, and Mox Opal by paying seven mana.
13. Repeat.