Karametra's Acolyte, and Umbral Mantle

Prerequisites

• Karametra's Acolyte on the battlefield
• Umbral Mantle on the battlefield
• Karametra's Acolyte does not have summoning sickness
• Your devotion to green is at least four

Steps

1. Activate Karametra's Acolyte by tapping it, adding at least
2. Activate Karametra's Acolyte by paying and untapping it, giving it +2/+2 until end of turn
3. Repeat

Results

• Infinitely large Karametra's Acolyte until end of turn
• Infinite green mana