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

Mirrodin Besieged
Myr Retriever
Scrap Trawler
Krark-Clan Ironworks

Requires
Myr Retriever in your graveyard. All other permanents on the battlefield. "Mirran" chosen with Mirrodin Besieged.
Steps
  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
Results
Infinite creature tokens. Infinite colorless mana. Infinite ETB. Infinite LTB. Infinite death triggers. Infinite sacrifice triggers. Infinite storm count.