Umbral Mantle, and Viridian Joiner

Prerequisites

• Umbral Mantle on the battlefield
• Viridian Joiner on the battlefield
• undefined at most available

Steps

1. Activate Viridian Joiner by tapping it, adding an amount of equal to its power
2. Activate Viridian Joiner by paying and untapping it, giving it +2/+2 until end of turn
3. Repeat

Results

• Infinite power for a creature until end of turn
• Infinite green mana