How can you create a combo with Urza, Prince of Kroog, Powerstone Shard, Akroma's Memorial?
user
[START OF COMBO]This combo can be formed with Urza, Prince of Kroog, Powerstone Shard, Akroma's Memorial

Color identity: WU
Mana cost: {13}
Steps:
  1. Activate Urza by paying {6}, 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 {C} for each Powerstone Shard you control.
  3. Repeat two additional times.
  4. Activate the original Powerstone Shard by tapping it, adding {C} for each Powerstone Shard you control.
  5. Repeat steps 1 through 3.[END OF COMBO STEPS]

Result:
  - Infinite colorless mana
  - Infinite enters the battlefield
  - Infinite tapped creature tokens[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
[END OF COMBO PREREQUISITES]
assistant