You have discovered what appears to be an investigative journal left behind by Magister Duskwither. A brief scan of its contents reveal some shocking attempts at filtering corrupted magical flows, which might explain what has happened here at Duskwither Spire. The magister is sure to want this brought back to him.
What's this? It looks familiar. Oh no, this journal... my investigations... this is what caused all of this in the first place.
Here it is, <name>, the proof of my crime. This journal contains all of my ill-conceived studies.
Heedless of the warnings, I continued my research, until it was almost too late. Then, when I grasped my error, I did what I could. But by then, some of my pupils had already gone too far. I evacuated the Spire to get them away from the corruption, but in my haste, forgot to shutdown the power sources.
I will burn this tome so that no one else falls prey to its contents. I only wanted to help the sin'dorei.