The Shadow Planetkiller is not really a ship per se. It is composed of a cloud of particles
(presumably nano-technology) and a huge superstructure capable of launching huge missiles.
When attacking a planet, the superstructure and cloud surrounds it, devouring the atmosphere
and everything in it, while thousands and thousands of missiles are lauched towards the surface.
These missiles drill down into the surface and explode, gradually tearing the
planet apart. The cloud can also be effective against ships, where the
cloud particles attach themselves and disable vital ship systems.
Nothing else is known about this peculiar weapon.
The Shadow Motherships are incredibly powerful ships, only rivaled in power
by Vorlon ships. They resemble huge black
spiders, with 10 spines sticking out on each side, and they are organic in nature.
Shadow Motherships are extremely maneuverable for ships of their size, they appear to be at least
1 km wide between the farthest "spine"-tips. The weapon of choice is an extremely
powerful beam weapon that easily slices through most ships and space stations.
They can also launch jump-point de-stabilizers, destroying ships that attempt
to escape. The Motherships also carry many Shadow fighters that can be launched
together. The Shadow Motherships enter and exit hyperspace by "phasing" in and
out of normal space, a more advanced and faster method than using jump-points.
This "phasing" is often mistaken for "cloaking", which it is not.
The Shadow Scout is a small ship, although much larger than a Shadow Fighter.
While it does not have a very powerful weapon, it is very maneuverable.
The Scout is used for scouting out an area before a Shadow attack. It can
phase in and out of hyperspace.
The Shadow Fighter is, like the Mothership, based on advanced organic
technology. It is very maneuverable, and its overall length appears to be
30-40 meters. It appears to have only one weapon, a "ball" of energy that it
shoots out of the frontal opening. As the Fighter fires, it expands and contracts,
earning its nickname "Spitfire". A Shadow Fighter can also phase in and out
of hyperspace on its own.