The Malfunctioning Geo-Borer
An ancient, brass-plated excavation machine fused into the cavern wall. Its massive central drill and various auxiliary pistons activate when they sense seismic vibrations, turning the cave floor into a blender of stone and steel.
The Malfunctioning Geo-Borer
Defenses
Detection
“A ten-foot diameter circular face of interlocking brass plates, housing a series of telescoping drill bits and jagged grinding wheels. Large copper pipes run from the machine into the surrounding limestone, occasionally venting high-pressure steam.”
Standard Engagement
A creature moves within 15 feet of the machine or makes a loud sound (such as a thunder-based spell).
The Geo-Borer has 3 actions. Action 1: Centrifugal Grind. Action 2: Scalding Exhaust. Action 3: Seismic Recalibration.
The machine powers down into a state of 'low-power seismic monitoring' after 1 minute of silence and no movement. It fully resets its internal tension springs over the course of 1 hour.
The machine spins its diamond-studded bits. All creatures in a 15-foot emanation must succeed at a DC 24 basic Reflex save or take 2d10+8 slashing damage. On a critical failure, the creature is also knocked prone by the vibration.
Vents on the machine's side release pressurized steam. All creatures in a 20-foot cone take 2d6 fire damage (DC 24 basic Fortitude save). The area becomes concealed for 1 round.
The machine pulses its sensors. Until the start of its next turn, it gains a +2 circumstance bonus to its AC and its saving throw DCs increase by 1 as it more accurately tracks its targets' movements.
If the Geo-Borer takes more than 10 points of cold damage from a single source, the brass plates contract, causing the machine to lose 1 action on its next turn.
After the machine completes its first routine, the floor within 15 feet of it becomes difficult terrain as the stone is turned to gravel.
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