The Acolyte Imperiled artifact weapon quest for many classes that face Agatha (Rogue, Mage, Warlock, Shaman, etc.) phases out and is unable to be completed since the War Within prepatch. It takes place under Legion Dalaran in the Chamber of the Guardian, and the NPC Ritssyn disappears when you are supposed to defend him. This blocks MANY classes from getting their artifact weapon and progressing their class order halls.
This is old but important content that needs fixing! It’s been more than 6 months without a fix…
Found this on WoWhead, maybe it will help:
"as of 2021, doing it as lv60 druid, first attempt, killed way too fast, bugged. Abandon, leave the building then get back in, retake the quest, and let the imp hit you for about 7mins or so, slowly kill one by one the quest will complete. AFTER THAT, only we are require to light up the runes lol "
Also found this:
"If you die, don’t release. The quest completed itself while I was reading the comments "
Has the character in question done the TWW prepatch quest chain (The Harbinger)? Or if the character is 70, have you done the initial TWW quests to reach Dornogal?
That quest chain phases the Chamber of the Guardian. Usually completing those quests will unphase the area.