Xorn, Black Market Tycoon, Umbral Mantle, and Goldspan Dragon

Prerequisites

• Xorn on the battlefield
• Black Market Tycoon on the battlefield
• Umbral Mantle on the battlefield
• Goldspan Dragon on the battlefield

Steps

1. Activate Black Market Tycoon by tapping it, creating two Treasure tokens
2. Activate both Treasure tokens by tapping and sacrificing them, adding
3. Activate Black Market Tycoon by paying and untapping it, giving itself +2/+2 until end of turn
4. Repeat

Results

• Infinite colored mana
• Infinitely large Black Market Tycoon until end of turn
• Infinite Treasure tokens
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinitely large creature until end of turn