From the back cover:
As the 13th Age unfolds, its mysteries - and dangers - grow more numerous.
Undreamed-of creatures crawl up from the underworld, descend from the sky on metallic wings, and slip through the cracks in reality. Strange magic is loose in the world, whether it's drawn from the Wild, from the realms of chaos and death, or from the inner power of ki.
Patch things up with your surly magic weapon, hero. The adventure is just beginning.
13 True Ways expands the 13th Age Roleplaying Game in exciting new directions. Within its 256 pages you'll find six new classes, the lore of devils, the keys to Horizon, the Great Gold Wyrm's secret assassin, and much more.
-The chaos mage who embraces randomness, and the monk who embodies discipline
-The druid who masters the elements, and the necromancer who commands the undead
-The commander who orders your ranks, and the occultist who orders reality
-Multiclassing tools to help you create the character you most want to play
-Treasure to loot, and artifacts that just might loot you
-All-new details and adventures seeds for Axis, the Court of Stars, Drakkenhall, Horizon, and Santa Cora
-More ways to use the icons, including relationship results tied to a location
-Lists for 13 deadly dungeons, flying realms, must-visit inns, and more
-Four detailed new NPCs with multiple campaign options
-New monsters to challenge your pliers, including devils, metallic dragons, were beasts, and should flensers
13 True Ways: New heroes. New legends. Your world.