Requires

Fertilid must be on the battlefield. Amulet of Vigor must be on the battlefield. Felidar Retreat must be on the battlefield. Regal Behemoth must be on the battlefield. Fertilid has at least two +1/+1 counters on it. You are the monarch. Mana needed:

Steps

1. Activate Fertilid, searching your library for a basic Forest card, putting it onto the battlefield tapped.
2. Amulet of Vigor triggers, untapping the land.
3. Felidar Retreat triggers.
4. Resolve the Felidar Retreat trigger putting a +1/+1 counter on each creature you control.
5. Tap the land for .
6. Repeat.

Results