Admittedly I had the benefit of completing the sig line once already, but my level 50 Defiler made it through with approximately the same number of deaths as the 100 Guardian who didn't get one shotted. Definitely doable with some patience and self-awareness.
Why is the BoL sig line needed to buy the new Acrylia adorn books? Is there some ridiculous reason for that, or do they have the wrong quest attached to them?