Ascalonian catacombs path 3 tzark bug
Did Tzark or Grast die during the 4 Burrows? If yes, then this is what causes that bug.
This has happened twice in two weeks to me. The first time we were able to fix it somehow as Tzark suddenly moved again. Probably because we were able to pull aggro on him from a spider but I’m not entirely sure. The second time I wasn’t able to fix it and was forced to leave the dungeon empty handed.
As for the cause of this bug, I think it has partially to do with Warmaster Grast dying due to the spiders and gravelings. So make sure you kill the little spiders that follow you up the stairs. Also killing the burrows too fast might be responsible for the NPC not following closely. Having two Elementalists in your team with ice bows and FGS makes you extra vulnerable to this bug.