Umbral Mantle, and Doc Samson, Super Psychiatrist

Prerequisites

• Umbral Mantle on the battlefield
• Doc Samson, Super Psychiatrist on the battlefield

Steps

1. Activate Doc Samson by tapping it, adding at least three mana of any color
2. Activate Doc Samson 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