Halaster's Riddle

 is the first quest in the Undermountain Campaign which takes begins in the Twisted Caverns campaign zone. This quest becomes available after completing both the previous quest, What Lies Below, and the third Undermountain campaign task, Expedition to Twisted Caverns. It is started by interacting with the Arch Gate plaque behind Azuli Tefnek.

Steps

 * Talk to the Stranger
 * Meet Sloopul
 * Return to the Alchemist