How can you create a combo with Mirror-Mad Phantasm, Unstable Shapeshifter?
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[START OF COMBO]This combo can be formed with Mirror-Mad Phantasm, Unstable Shapeshifter

Color identity: U
Mana cost: {4}{U}{U}{U}
Steps:
  1. Cast Mirror-Mad Phantasm by paying {3}{U}{U}.
  2. When Mirror-Mad Phantasm enters the battlefield, Unstable Shapeshifter triggers, causing Unstable Shapeshifter to become a copy of Mirror-Mad Phantasm until end of turn.
  3. Activate Unstable Shapeshifter by paying {1}{U}, shuffling Unstable Shapeshifter into your library and milling your entire library due to it not having a card named Mirror-Mad Phantasm in it.[END OF COMBO STEPS]

Result:
  - Infinite self-mill[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Mirror-Mad Phantasm must be in your hand
  - Unstable Shapeshifter must be on the battlefield
[END OF COMBO PREREQUISITES]
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