Halas' captive astral dreadnought

This astral dreadnought was encountered by the Mighty Nein in the Astral Plane via the Folding Halls of Halas.

Appearance
This astral dreadnought was 20 to 25 feet on a side, though its silvery tail seemed to curl off into an impossible distance. It was shaped like a bulbous, muscular serpent with two thick arms ending in pincers. Its body was covered in spiky armored plates and hardened, veiny, pale flesh plates. Its face had a single eye with a horned brow and a 12-foot-wide mouth edged with hundreds of two-foot-long teeth. Halas Lutagran kept this astral dreadnought chained and blinded, with a lever controlling the opening and closing of its mouth, so that he could use the capacious demiplane within as a ritual chamber.

Skills and Abilities

 * Demiplanar Donjon: The Mighty Nein entered the dreadnought's mouth to find a demiplane that Halas had used.


 * Given that Halas kept a large platinum plate bolted over the dreadnought's eye, this astral dreadnought likely has the same ability as in Mordenkainen's Tome of Foes: creating an antimagic cone.

Trivia

 * Knowing that Vokodo had desperately fled from something in the Astral Sea, Fjord used Major Image to create an illusory, smaller-than-usual astral dreadnought to frighten Vokodo during their battle. Despite Fjord having to guess at what an active dreadnought sounds like, the illusion worked: Vokodo was chased around the lair.