Skitterlings

Creatures from the Abyss, Skitterlings are usually summoned as the shock troops of powerful Demonologists. Their glittering black exoskeleton almost glows with a faint magic aura. The Skitterling is a biped with an obsidian black exoskeleton, four blade like arms, and glowing green eyes.

They are extremely quick, and can scale sheer surfaces. They are Outsiders, creatures of the Abyss, which exist only to kill. Not very intelligent, they are excellent at following instructions and are often the shock troops of more powerful demons, agents of Chaos or powerful sorcerers who specialize in Demonology. Individual Skitterlings will sometimes be directed to hunt a specific individual, and will stop at nothing to make the kill. terrifying creatures of chaos and evil. Frequently seen throughout the reign of the second Dark Emperor. Bipedal, about seven feet tall, with four arms, each ending in a bonelike blade. Ink black in color, with glowing green eyes. They are named for the sound they make as they approach their prey.

Because they're so infrequently seen, many people believe that the skitterlings are just myths and stories.