This section includes material for use by the Keeper of Arcane Lore, Call of Cthulhu's name for the Game Master. There are few changes from previous editions, but plenty of additional material. The most immediately useful of these additions are devoted to advice on running a Call of Cthulhu game. Although previous editions of the game have included advice, it's good to see even more of it in this edition. Call of Cthulhu is an acquired taste and, as such, its mysteries take time to master.
More advice is thus a welcome addition to the game.
I'm glad to see this included, as I think previous editions have neglected the science fictional elements integral to Lovecraft's stories. This edition also includes a listing of all Mythos spells published in the game's long existence, making it a nice compendium for the completist. All have appeared in previous editions. Interestingly, two of them first appeared in the first edition that introduced me to the game many moons ago. Nevertheless, it's good to see so many scenarios included in the basic game book.