The Festival of the Founding was a celebration held in Menzoberranzan on Ches 20 every year to commemorate the anniversary of Menzoberranzan's founding by Menzoberra the Kinless. Unallied houses were to dine together as a display of unity. Sometimes Lolth appeared in the form of an avatar.
The first house, House Baenre, usually held only a cursory celebration. However, in 1484 DR, Quenthel Baenre and her contingent dined with House Fey-Branche, where the Yor'thae (Danifae Yauntyrr) of Lolth appeared to them, indicating that Quenthel was in the Spider Queen's favor.