Umbral Mantle, and Mona Lisa, Science Geek

Prerequisites

• Umbral Mantle on the battlefield
• Mona Lisa, Science Geek on the battlefield
• at most available

Steps

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

Results

• Infinite colored mana
• Infinite mana creatures you control can produce
• Infinite untap of creatures you control
• Infinitely large creature until end of turn