Retreat to Coralhelm + Azorius Chancery + PuPu UFO

Retreat to Coralhelm

Azorius Chancery

PuPu UFO

How it works

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