How can you create a combo with Hylda of the Icy Crown, Intruder Alarm, Ashnod's Altar, Court Street Denizen?
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[START OF COMBO]This combo can be formed with Hylda of the Icy Crown, Intruder Alarm, Ashnod's Altar, Court Street Denizen

Color identity: WU
Mana cost: 
Steps:
  1. Cause a white creature to enter the battlefield under your control.
  2. Intruder Alarm and Court Street Denizen trigger.
  3. Resolve the Intruder Alarm trigger, untapping all creatures.
  4. Holding priority, activate Ashnod's Altar by sacrificing the white creature, adding {C}{C}.
  5. Resolve the Court Street Denizen trigger, tapping an opponent's creature.
  6. Hylda of the Icy Crown triggers, causing you to pay {1} to create a 4/4 Elemental creature token.
  7. Repeat from step 2.
  8. Once you have infinite mana, you may forego sacrificing the Elemental tokens.[END OF COMBO STEPS]

Result:
  - Infinite colorless mana
  - Infinite creature tokens
  - Infinite death triggers
  - Infinite enters the battlefield
  - Infinite leaves the battlefield
  - Infinite mana creatures you control can produce
  - Infinite sacrifice triggers
  - Infinite untap of all creatures[END OF COMBO RESULT][END OF COMBO]

Other prerequisites:
  - All permanants must be on the battlefield
  - An opponent controls a creature.
  - You have a way to cause a white creature to enter the battlefield under your control.
[END OF COMBO PREREQUISITES]
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