I'm going to start by saying that I'm never sure how to handle spoilers when reviewing an older book. This was published in 2000, so I really think that after 22 years (!!), the spoiler period has ended. On the other hand, I just read this for the first time, and obviously there will be others as well. So I'm going to touch on some spoilers in broad strokes, but I will try to avoid going into too much detail or will spoiler-tag. But there's no way to discuss this without at least some detail, so take your warnings now if you want an absolute blank slate for your read through.
I was uncertain what to expect as I headed into this, the final book in the quintet, when the fourth book felt like it was closing the series out. However, this turned out to be a true bookend to the story, as we return to the people and places that started it all--Kierkan Rufo, Druzil, the Edificant Library, and...the chaos curse.
Based on the indications we'd previously been given, I was expecting the plot of this book to focus on Cadderly's attempt to wrench the order of Deneir and the Library into his way of thinking. That was all I could think would be the main conflict, since the major Big Bad had been defeated in the previous book. I would never have foreseen a situation where Kierkan Rufo becomes the major threat.
There is a lot worth covering here, although I'm going to skip past the edges of some of it. I loved the way that the takeover of the Library was accomplished, and the endings experienced by those that accepted the 'offer' of being turned versus those who held on to their faith until the last. Also, Pikel managed to become a druid and to perform priestly and clerical feats, apparently by will and force of belief alone. I have no idea how and...honestly, the idea that he did it all on his own, I kind of love. Pikel's determination to be a druid was treated as something of a punchline through the first three books, but it wasn't there just for comedic value, and I'm glad that he received at least some of the recognition he deserved by the end.
The part that frustrated me the most (aside from the ending, which made me cry) was the fact that every single one of Our Heroes that came near the Library after it had fallen managed to not notice that it had been desecrated. I find it hard to believe that every single one of them managed to be so distracted that they didn't notice the warning signs, and didn't attempt to leave immediately after entering the Library, even though by then they knew something was wrong. It felt a bit forced, since they had to enter the Library in order for the plot to move forward, and there didn't appear to be an in-character way to get them in, they all went momentarily stupid. (As a different reviewer said, all of them crit failed.)
Maybe we can assume that the curse was affecting them before they were even in the library, preventing them from noticing the warning signs until it was too late. Yes, we'll go with that.