A spiral metal staircase leads upwards.
|The staircase deploys blades and starts to spin when activated.
A DC 14 Wisdom (Perception) check reveals several small openings in the central pole of the staircase. Closer inspection with a DC 14 Intelligence (Investigation) check allows the target to discover that each opening contains a blade. One of the openings seems to contain a spring attached to one of the stairs.
A DC 16 Wisdom (Perception) check reveals a small, circular wear pattern at the top and bottom of the pole. Further investigation via a DC 16 Intelligence (Investigation) check reveals that the pole goes down into a gear in the floor.
If the stair is depressed, the center pole begins to spin as the blades deploy. All targets on the staircase must make a DC 10 Dexterity saving throw or be thrown from the staircase, taking 2d6 bludgeoning damage.
Those that stay on the staircase suffer a +8 melee attack each round for 3d6 slashing damage from the blades.
Moving on the staircase is at half speed, and requires a successful DC 10 Dexterity (Acrobatics) check. Failure results in being thrown from the staircase as above.
The stair can be disabled with a successful DC 14 Dexterity check with thieves’ tools. Failure results in triggering the trap.
The pole can be disabled with a successful DC 16 Dexterity check with thieves’ tools to jam the gears. If the gears are jammed, the blades will still be deployed. At deployment, targets on the stairs will be subjected to a +2 melee attack for 1d6 slashing damage. Moving up the stairs with the blades deployed requires a successful DC 14 Dexterity (Acrobatics) check. Failure results in 1d6 slashing damage.
Each blade can be disabled with a DC 12 Dexterity check with thieves’ tools. Failure results in a +2 melee attack for 1d4 slashing damage.