There's another solution, it's a cheese but, well, on the first run, if you're really struggling, it's ok to cheese sometimes.
While your character talking to aetera, use another character to teleport her and your main very far from the hounds (when i tried this, i almost reach the entrance of the area). When you're done, start the fight. You'll destroy aetera before the hounds are able to even come in range.
As i said, it's a cheese, but it works.
