From the publisher's website:
Let us have a moment of silence for the defeated monsters.
Now, let us take their stuff.
What’s In This Book:
That’s both an answer and an exhortation. Yes, 13th Age is all about the story and the awesome action, but we’ve all got a treasure-hungry munchkin inside of us, and it’s time to let that grubby-fingered kid out to play.
The Book of Loot is full of more magic items to be found, stolen, given as rewards or otherwise looted by the player characters. We’ve also thrown in a short chapter on ways to make mundane treasure more interesting, and a selection of new one-use magic items.