Similar to nautiloids in design, a dreadnought consisted of two large nautiloid hulls upon which a gigantic snail shell rested on its side. One of the hulls was used for the command stations and the other for battle and ramming.
A typical dreadnought had a crew of 25 mind flayers. It could support up to 90 creatures without compromising its air supply.
In the late 15th century DR, when nautiloids had become increasingly rare, an exceedingly small number of mind flayer colonies still had access to this large vessel. The dreadnoughts were employed as mobile lairs that the colony could use to engage in hit-and-run raids. For that reason, colonies that had access to these immense ships were much more aggressive than usual. To protect themselves from enemies, these colonies usually made their lairs in mountaintops or submarine locations, but could also just remain constantly flying, safe from raids in high altitudes.