Chromatic Star's ability, allowing you to activate mana abilities while delaying any triggered abilities until this ability has finished resolving.
Activate
Mana Crypt's mana ability by tapping it, adding ({C} magic symbol) ({C} magic symbol) .
Activate
Krark-Clan Ironworks three times by sacrificing
Mana Crypt,
Myr Retriever, and
Krark-Clan Ironworks, adding six colorless mana.
Complete the activation of
Chromatic Star by paying ({1} magic symbol) , tapping it, and sacrificing it, adding one mana of any color.
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.
Resolve
Chromatic Star's triggered ability, drawing a card.
Resolve
Myr Retriever's triggered ability, returning
Krark-Clan Ironworks from your graveyard to your hand.
Resolve
Scrap Trawler's triggered ability from
Krark-Clan Ironworks, returning
Myr Retriever from your graveyard to your hand.
Resolve
Scrap Trawler's triggered ability from
Myr Retriever, returning
Chromatic Star from your graveyard to your hand.
Resolve
Scrap Trawler's triggered ability from
Chromatic Star, returning
Mana Crypt from your graveyard to your hand.
The final
Scrap Trawler triggered ability from
Mana Crypt fails to resolve due to lack of targets.
Cast Krak-Clan Ironworks, Myr Retriver,
Chromatic Star, and
Mana Crypt by paying seven mana.
Repeat.
Notes
The purpose the delay mentioned in step 1 is to wait until all relevant artifacts are in your graveyard before you have to select targets for triggered abilities.