The reward book is a reward given to players who tested the Combat Academy. After finishing a section in the combat academy, the player can open the course interface and right-click on the rank and select Claim-Reward to claim the book. If all 21 sections were completed, 21 books will be given. They can also be claimed from Lady Deathknell.
The books can give experience in one of any of the following skills: Attack, Strength, Defence, Constitution, Ranged, Magic, Prayer, Herblore, Summoning, Slayer