Retreat to Coralhelm + Boros Garrison + PuPu UFO

Retreat to Coralhelm

Boros Garrison

PuPu UFO

How it works

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