Umbral Mantle, and Viridian Joiner

Prerequisites

• Umbral Mantle on the battlefield
• Viridian Joiner on the battlefield
• 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 green mana
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinitely large creature until end of turn