Retreat to Coralhelm + Ghost Town + Scaled Herbalist

Retreat to Coralhelm

Ghost Town

Scaled Herbalist

How it works

1. During any opponent's turn, activate Scaled Herbalist by tapping it, putting Ghost Town from your hand onto the battlefield.
2. When Ghost Town enters the battlefield, Retreat to Coralhelm triggers, untapping Scaled Herbalist.
3. Activate Ghost Town's first ability by tapping it, adding C.
4. Activate Ghost Town's second ability by paying 0, returning it from the battlefield to your hand.
5. Repeat.