Mechanus is a plane of existence—the lawful neutral plane of pure order and clockwork machinery. In the Tomb of the Nine Gods, Acererak has hijacked a workforce of modrons from Mechanus to power his tomb’s machinery.
Connection to the Tomb
Acererak contaminated a workforce of modrons and, under the stewardship of a corrupt pentadrone, caused them to reroute one of Mechanus’s great chains into the tomb. The chain appears in area 69 of the tomb, where it rattles through a forty-foot-diameter vertical shaft between two stone balconies. The shaft sections above and below the balconies exist outside of normal space, preventing intersection with the tomb’s other levels.
The Mechanus Chain
The repurposed Mechanus chain drives the tomb’s infernal machinery and keeps traps and mechanisms in working order. Such chains are normally crafted by modrons to keep the plane of Mechanus functioning.
Physical Description
- Hot wind tinged with burning oil blows through the shaft
- Two thick chains rattle through the gulf between balconies
- One chain ascends 200 feet before disappearing into a cloudy vortex lit by purple lightning arcs
- The other wraps around an enormous metal gear floating 100 feet below
- A second vortex rages another 100 feet below the gear
Game Mechanics
- Planar vortices are incredibly destructive—no one can expect to survive entering one
- Destroying a Mechanus chain requires casting three wish spells
- One chain is sufficient to power all the tomb’s traps and mechanisms
Modron Defense Force
When characters first move onto a balcony at the Mechanus chain shaft, a pentadrone leads nine quadrones through the upper planar vortex. The vortex allows safe passage into the shaft but not out of it. Knowing they cannot return to Mechanus, the modrons fight to the death. Once defeated, no additional modrons are sent.
The pentadrone travels inside a crystal decahedron vehicle (AC 16, 50 hp, immune to poison, resistant to piercing/slashing, vulnerable to bludgeoning/thunder). The vehicle grants the pentadrone total cover from outside attacks and a flying speed of 30 feet with hover. The pentadrone can open small holes in the facets to spray paralysis gas as a bonus action. When the pentadrone dies or the vehicle is destroyed, the decahedron shatters.
The Mechanus Wardrobe
A magical wardrobe in the tomb depicts an ornate clock face on its door. When opened, it reveals enormous interlocking gears and cogs stretching into the distance—a view of Mechanus itself. A single clueless, disoriented monodrone tumbles through and lands prone. The modron attempts to return through the wardrobe but is rebuffed by its magic. It fights only in self-defense and disintegrates if destroyed.