The Advanced Fantasy Referee's Tome is the essentials referee's guide to Old-School Essentials Advanced Fantasy games, with the following content:
Guidelines: Full guidelines for designing and running adventures.
Monsters: A selection of over 300 fearsome monsters to challenge adventurers of all levels.
Treasures: A hoard of over 300 wondrous magic items.
Includes all referee guidelines, monsters, and treasures from Old-School Essentials Classic Fantasy, plus reams of additional material inspired by the 1970s Advanced 1st Edition rules.