Abhorsen by Garth Nix is the final book in the Abhorsen/The Old Kingdom trilogy though there have been more books added to the series since this ones publication. This book follows Lirael and Sam as they try to save Sam’s friend Nick and stop the necromancer Hedge from awakening the Destroyer. As the Destroyer is the enemy of all life and must be stop which only an Abhorsen can do however, there has been no word from the current Abhosren Sabriel and King Touchstone.
In comparison to the second book which focuses more on set up this one is very action and plot heavy and ultimately feel like if the second and third books had been combined I would have enjoyed the full story more. This series is a reread for me though I haven’t read the series in many years because of that while I liked the series overall I feel like Sabriel works better as a stand a lone book. However, If you liked Sabriel I do think you should try the other books in the series.