Infinite creature ETBInfinite creature tokensInfinite untap of creaturesInfinite mana creatures you control can produceInfinite unlocking of Rooms you control
How it works
Activate any number of creatures you control by tapping them, adding at least enough mana to unlock a locked Room you control.
Unlock any Room you control by paying its mana cost.
Ghostly Dancers' second ability triggers, creating a 3/1 Spirit creature token.
When the Spirit enters the battlefield, Intruder Alarm triggers, untap all creatures.
Activate Marina by tapping it, locking the Room that was unlocked in step 1.