Sai, Master Thopterist + Myr Retriever + Workshop Assistant + Krark-Clan Ironworks

Sai, Master Thopterist
Myr Retriever
Workshop Assistant
Krark-Clan Ironworks

Requires
Myr Retriever in your graveyard. All other permanents on the battlefield.
Steps
  1. Activate Krark-Clan Ironworks by sacrificing Workshop Assistant, adding cc
  2. Workshop Assistant dies, returning Myr Retriever from your graveyard to your hand
  3. Cast Myr Retriever by paying 2
  4. Sai triggers, creating a 1/1 Thopter artifact creature token
  5. Activate Krark-Clan Ironworks twice by sacrificing the Thopter and Myr Retriever, adding cccc
  6. Myr Retriever dies, returning Workshop Assistant from your graveyard to your hand
  7. Cast Workshop Assistant by paying 3
  8. Sai triggers, creating a 1/1 Thopter 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.