Driders were cursed Dark Elf that had been punished for failing a test of Unknown. From the waist down, their bodies transformed into the massive, chitinous form of a giant spider, complete with eight spindly legs and a bulbous abdomen. The creation of a drider was an agonizing process, but resulted in a creature that kept all magical abilities and skills while being physically far more fearsome. In the process, driders became sexless, as Lolth did not want to create a race of enemies to the drow.
Driders could reliably climb like spiders, though their weight prevented them from walking upside down on ceilings. They possessed the deadly agility and venomous bite of a giant spider, coupled with the spellcasting prowess and ruthless intelligence of a drow. Their webs could trap the unwary, and their darkvision allowed them to see clearly in the pitch-black depths of their Underdark domain.
Their transformation drove driders to madness, and they typically disappeared into the Underdark to become hermits and hunters. Generally unstable in their mental state, they would either wander alone or lead packs of giant spiders. On rare occasion, a drider would return to the fringes of drow society despite its curse, most often to fulfill some longstanding vow or vendetta from its former life. Drow feared and shunned the driders, holding them in lower esteem than slaves. However, they tolerated the presence of these creatures as living representatives of Lolth's will, and a reminder of the fate that awaited all who failed her.