Yochlol

A yochlol was a type of lesser demon that acted as "handmaidens" to Lolth, the drow goddess of chaos. Their natural home was the Demonweb Pits. Only high priestesses of the Queen of Spider's were told how to summon a yochlol. They were only supposed to be called upon in dire need or to witness sacrifices in the name of their dark goddess.

In their natural form they appeared as tentacled blobs of melted wax and continually emitted a foul stench. They also had the power to change their shape—usually to a comely drow female (although other elves and humans were also possible) or to a large spider (usually a black widow). They could also change into a gaseous form, allowing their unknowing victims to inhale them, and then suffocate.

Lloth created the Yochlol from succubi that she captured from layers of the Abyss. She never revealed how she transformed the succubi into yochlols, but when the process was completed, the yochlol remembered nothing of its former life and was completely loyal to their new mistress.

Nature
Like all tanar'ri, yochlols were chaotic evil creatures. They took great pleasure in dominating other creatures. They were cruel and enjoyed a good battle, exulting in the rage that filled them whenever beings defied their goddess's will. All yochlol served Lolth and worked surprisingly well together. One would never betray, endanger, or attack another. All yochlol shared a telepathic bond. Summoned yochols must faithfully serve one deed to their summoner. They took special delight in escaping the control of those who summoned them, and wandered free about the Prime Material Plane. Yochlol used various forms as disguises to carry out cunning ploys and evil subterfuges to turn beings to chaos and evil. Unless enemies of Lolth were present, yochlols would not engage in killing sprees or frenzies of mindless violence. Yochlol often hiss, whisper, or scream when in combat, even telling their opponents their names, in case the victim should escape. That way, the victim knew that a particular Handmaiden somewhere would eventually return to finish its business with them.