Urza, Prince of Kroog, Encroaching Mycosynth, Training Grounds, and Grand Architect

Prerequisites

• Urza, Prince of Kroog on the battlefield
• Encroaching Mycosynth on the battlefield
• Training Grounds on the battlefield
• Grand Architect on the battlefield
• available

Steps

1. Activate Urza by paying , creating a token copy of Training Grounds that is a 1/1 Soldier in addition to its other types
2. Activate Grand Architect's second ability by tapping the Training Grounds token, adding that can only be spent to cast artifact spells or to activate abilities of artifacts
3. Activate Urza by paying at most , creating a token copy of Training Grounds that is a 1/1 Soldier in addition to its other types
4. Activate Grand Architect's second ability by tapping the Training Grounds token, adding that can only be spent to cast artifact spells or to activate abilities of artifacts
5. Repeat from step 3
6. Once you have infinite colorless mana, you may target any other nonland permanent using Urza's ability

Results

• Infinite colorless mana that can only be spent to activate abilities of artifacts
• Infinite colorless mana that can only be spent to cast artifact spells
• Infinite copies of nonland permanents you control
• Infinite creature tokens
• Infinite ETB