Retreat to Coralhelm + Rakdos Carnarium + PuPu UFO

Retreat to Coralhelm

Rakdos Carnarium

PuPu UFO

How it works

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