Urza, Prince of Kroog, Powerstone Shard, and Akroma's Memorial

Prerequisites

• Urza, Prince of Kroog on the battlefield
• Powerstone Shard on the battlefield
• Akroma's Memorial on the battlefield
• available

Steps

1. Activate Urza by paying , creating a token copy of Powerstone Shard that is a 1/1 Soldier in addition to its other types
2. Activate the Powerstone Shard token by tapping it, adding for each Powerstone Shard you control
3. Repeat two additional times
4. Activate the original Powerstone Shard by tapping it, adding for each Powerstone Shard you control
5. Repeat steps 1 through 3

Results

• Infinite colorless mana
• Infinite ETB
• Infinite tapped creature tokens