Attack of the Fiend has been my favorite book in the Last Apprentice series so far.
Thomas has come a long way since the day he left his family's farm to be an apprentice to the local Spook. More and more Thomas is learning that he cannot just blunder his way through being a Spook with blind luck and using his head. Taking what the Spook has taught him Thomas has used all that knowledge to his advantage. While Thomas still struggles it is clear that he is growing up and becoming more a Spook then a lucky person.
Alice continues to mystify as she once again walks the line between good and bad. It is still not clear what Alice's fate will be but it is clear that her feelings for Tom are evolving. While I still want to see some of the story from Alice's point of view I do enjoy that she is a mystery and constantly keeping me guessing on what she will do.
Everything continues to get darker, the world is facing an intense darkness and it appears that Tom will be the one to battle that darkness one day. The evil in Attack of the Fiend was the best so far in my opinion. It kept me turning pages to find out what happened and I want more evil that wants nothing but to be evil.
I am eagerly looking forward to the next book in the series.