Runemastery is a great buy! It's well organized, easy to read, complete, and it makes me want to try it. There are detailed descriptions of 20 different runes, each with three different functions. There is plenty of diversity because you get to choose which order to learn the runes in. You also can inscribe runes onto just about any surface, like weapons and armor, or even yourself. This document provides everything you need to make your character a master of runes in one of four different subclasses, each of which looked fun to play. It looks like it belongs in the class section of the PHB. If you want a new class to try out, this product won't let you down.
On an unrelated note, this is Rory, not Rebecca s.