Gyre Engineer, Umbral Mantle, and Training Grounds

Prerequisites

• Gyre Engineer on the battlefield
• Umbral Mantle on the battlefield
• Training Grounds on the battlefield
• Umbral Mantle attached to Gyre Engineer
• Gyre Engineer does not have summoning sickness

Steps

1. Activate Gyre Engineer by tapping it, adding
2. Activate Gyre Engineer by paying and untapping it, giving itself +2/+2 until end of turn
3. Repeat

Results

• Infinitely large Gyre Engineer until end of turn
• Infinite green mana
• Infinite blue mana