The School of Potions and Poisons was a viaduct school on Sanctaphrax that sold potions, remedies, poisons, and other little-known concoctions from the Deepwoods. It was located in a run-down building on the Viaduct, with a stuffed vulpoon hanging over the door. It was mentioned in The Winter Knights.
Vilnix Pompolnius frequented the School of Potions and Poisons, purchasing toxic substances which he used to exact revenge on those he disliked. One such item obtained from the school, a vial of woodwasp eggs, was used to murder the Hall Master of High Cloud, Hax Vostillix. Eventually, this practice led to his expulsion from the Knights Academy.