>b-but the Netherstorm quest!!!!
Metzan and other devs have said before that Dimensius' showing up there was a mistake by the quest designers. They literally just pulled a cool sounding name from their lore books because they needed an elite to kill but were unaware of how important he was lore wise

If you want to talk about something in TBC, talk about Murmur
>lore wise no one knows what he is or where he came from
>not an elemental, demon or void creature
>the mere act of him entering the dimension was enough to destroy auchindoun
Probably one of my favorite monsters from this game. He makes weird unsettling noises, has next to no explanation or lore and then just leaves