Guard Zenath:
Breath of Death is a type of black magic. It's energy that can rise the dead. It haven't been used for a while, but it seems that's the case now.
Kill Spartoi Soldiers and Raging Spartoi, get Breath of Death from their remnants. If they are indeed influenced by that magic, it will leave traces on their bones.
I will teleport you to the place you need, don't waste time.
By the way, if you aren't familiar with potion auto-use function, please, look into Help menu. It is a very useful thing, I assure you.
Teleport