Myr Welder, Umbral Mantle, and Bag End Banquet

Prerequisites

• Myr Welder on the battlefield
• Umbral Mantle on the battlefield
• Bag End Banquet in exile

Steps

1. Activate Myr Welder using Bag End Banquet's ability by tapping it, adding at least Activate Myr Welder by paying and untapping it, giving it +2/+2 until end of turn
2. Repeat

Results

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