The Mages' book is a book held in place of a shield that is a reward from the Mage Training Arena minigame, and was also a rare potential drop from PvP worlds or Bounty worlds until its removal from the PvP drop table on 16 June 2009. The mages' book requires 60 Magic to wield and is held in the shield slot. It is commonly accepted as the hardest book to obtain in the game.

A mages' book can be obtained from the Rewards Guardian in exchange for 500 telekinetic, 550 alchemist, 6,000 enchantment, and 500 graveyard pizazz points. It is currently the most expensive reward available from the Rewards Guardian.

Until the release of spirit shields, the mages' book provided the highest Magic attack and Defence bonus of any item worn in the shield slot. These statistics can now be claimed by the Arcane spirit shield and Spectral spirit shield. The mages' book has the third-highest Magic attack bonus for any piece of equipment in the shield slot, the highest being the Arcane spirit shield and the second highest being the Farseer kiteshield. It has the Third-highest Magic defence for a shield, the highest being the Spectral spirit shield and the second highest being the Eagle-eye kiteshield.