How the game handled quests and areas and respawning had been changed and improved since last year. Previously, quest monsters only appeared if you had received the quest. You could clear out an area, return to town, get a quest to kill a monster in that area, and return to find dozens of corpses, and the one quest monster standing alone amidst your handiwork. This doesn't happen anymore, and now when you clear an area and then go back for a quest, the area has completely or largely respawned. The respawn happens with the monster type you need for the quest, logically enough.
