Retreat to Coralhelm + Orzhov Basilica + PuPu UFO

Retreat to Coralhelm

Orzhov Basilica

PuPu UFO

How it works

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