The Mages' book is a book used as an offhand weapon for spell-casting. The Mages' book requires 60 Magic to wield and is held in the offhand slot. It has the exact same stats as a grifolic orb but is much more expensive and requires a lot more effort to obtain, but may be recoloured in exchange for loyalty points.
On 7 September 2014, the price that a Mages' book could be bought on the Grand Exchange fell sharply from around 500,000 to around 30,000. The cause was never officially stated by Jagex. Mod Tyran stated that it was not caused by an in-game glitch or item duplication. On 8 September 2014, Jagex began removing the excess Mages' books from players that had purchased bulk amounts of them in the previous 24 hours, without refund.