The Royal Ranger

If you like ranger's apprentice, don't read it. There's a huge timeskip, Will is drastically different from the other books, the general feel & atmosphere of the book is drastically different from all the other books, and the book changes the focus to a new character who is not interesting in any way and is mostly a blend of two other characters in the books. During the timeskip two major characters were also killed without a proper goodbye or even a good reason and Will is no longer a kid and a completely different person who's basically just depressed and sad the whole time .

One of the worst books I've read in a long time, not necessarily on it own, but in the context of the series.