How can you create a combo with Great Whale, Cavern Harpy, Panharmonicon?
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[START OF COMBO]This combo can be formed with Great Whale, Cavern Harpy, Panharmonicon

Color identity: UB
Mana cost: {2}
Steps:
  1. Activate up to seven lands you control by tapping them, adding at least {2}{U}{U}{B}.
  2. Cast Great Whale by paying {5}{U}{U}.
  3. Great Whale enters the battlefield, triggering its ability twice.
  4. Resolve the first Great Whale trigger, untapping the seven lands.
  5. Activate the seven lands by tapping them, adding at least {2}{U}{U}{B}.
  6. Resolve the second Great Whale trigger, untapping the seven lands.
  7. Cast Cavern Harpy by paying {U}{B}.
  8. Cavern Harpy enters the battlefield, triggering its ability twice, returning Cavern Harpy and Great Whale from the battlefield to your hand.
  9. Repeat.[END OF COMBO STEPS]

Result:
  - Infinite enters the battlefield
  - Infinite leaves the battlefield
  - Infinite mana lands you control can produce
  - Infinite storm count[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - Great Whale must be in your hand
  - Cavern Harpy must be in your hand
  - Panharmonicon must be on the battlefield
  - You control up to seven lands that can tap to produce at least {2}{U}{U}{B}.
[END OF COMBO PREREQUISITES]
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