However, if you die during this step, they'll revert to being non-aggro.
Head down into the waterway. Enter the waterway, swim left and click on the grate to enter a sub-instance, Talthallas's Hidden Chamber
Confront Talthallas! He's in the south corner of the room, on the ceiling, upside down. Turns out he's a vampire. Talk with him a while and he'll fly away.
Defeat the vampire infestation!
Four New Tunarian vampires will spawn, first two individually (scales, even) and then a group of two (scales, one even one v). Kill them all to update.