Patron of the Moon + Arid Archway + Horizon Explorer

Patron of the Moon

Arid Archway

Horizon Explorer

How it works

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