https://wiki.project1999.com/Toxdil%27s_Poison
Quest works fine, but Toxdil does not respond to variations of "What deadly liquid," at indifferent.
He should say, "TThe deadly liquid I offer to rogues is called snake venom. I will be glad to make it for you, but first you must supply me with two snake venom sacs and my fee of 20 gold pieces. You may find the sacs upon the giant snakes of the Commonlands.'"