Retreat to Coralhelm + Izzet Boilerworks + PuPu UFO

Retreat to Coralhelm

Izzet Boilerworks

PuPu UFO

How it works

1. Activate PuPu UFO by tapping it, putting Izzet Boilerworks from your hand onto the battlefield.
2. When Izzet Boilerworks enters the battlefield, it and Retreat to Coralhelm trigger.
3. Resolve the Izzet Boilerworks trigger, returning itself from the battlefield to your hand.
4. Resolve the Retreat to Coralhelm trigger, untapping PuPu UFO.
5. Repeat.