13th Age is possibly the best RPG System I can remember since the First Edition of West End's Star Wars. The System itself is an amalgam of the best parts of OSR/3E/4E and each of the "main" Rulebooks (including this one) has indispensable guidance for advancing Creatures and making them your own. It's a clean, logical, AND immersive/evocative set of Rules that I believe you can do anything with. The writing and art are "Grade A" meaning you can tell right away that this is a product from some of the very best talents in the industry.

13 True Ways is critical as it has the "Good" Dragons, Lycanthropes, Mind Flayers (I mean "Flensers"), and Devils you don't want to miss.

Even though it's not advertised as a "Universal" Toolkit I honestly believe I could run ANY type of campaign with the 13th Age System. It's that good.