Patron of the Moon + Boros Garrison + Horizon Explorer

Patron of the Moon

Boros Garrison

Horizon Explorer

How it works

1. Pay 1 to activate Patron of the Moon, putting Boros Garrison from your hand onto the battlefield untapped due to Horizon Explorer.
2. When Boros Garrison enters, it triggers.
3. Activate Boros Garrison by tapping it, adding two mana.
4. Resolve Boros Garrison's triggered ability, returning it from the battlefield to your hand.
5. Repeat.