Boss rush is a game mode introduced in V1.12 that puts the player against only bosses and minibosses.
Boss rush is activated by talking to Sir Goodspeed in the bottom left corner of the hub after beating council members 3 times. For 10 chaos gems, he will activate the entry portal next to him that can be entered to begin boss rush.
Cursed relics sold by Nox in the plaza and gold given by Jade will be removed upon starting boss rush.
On the miniboss floors, the level layout is fixed with a central room where the boss fight takes place and 4 adjacent rooms. The room to the left will always be Artisan Andres (relic shop), down Nox the Unfortunate (cursed relics), right Virtuoso Iris (arcana shop), and the top being one of Doctor Song, Taffy the Pinata, Cremire the Collector, or Nocturne the Cardist.
Double Trouble will always be stocked by Nox on the first floor.