The Holy book is a book held in place of a shield, and is the god book aligned with Saradomin. God books are commonly used for their prayer bonus, something few shields offer. The Holy book is obtained from the Horror from the Deep quest. The book is received from the quest as just a cover, and requires 4 pages obtained from Treasure Trails to be completed. The book will not give any bonuses (with the exception of the +5 prayer bonus) until it is completed. With 50 Prayer and a completed book, players can enchant unblessed symbols into Holy symbols.
Equipping a holy book allows the player to preach and perform ceremonies, such as blessing, last rites, and wedding rites, by operating it (none of which have any effect on the game itself, and are simply recited lines of text), costing 25% of the player's special attack energy.
Lost holy books can be reclaimed by speaking to Jossik, complete with all pages that have been added, for no cost. Alternatively, for those who do not wish to travel to the lighthouse, Perdu will return them to players for 14,000 coins.
Filling the holy book currently costs 11,569 coins when buying each page individually or 16,330 when buying the item set.