From publisher blurb:
It is a rare thing that such ancient works of history are laid out so plainly, but leave it to the dwarves to do so. In a recent investigation of Kaza’Narth, one of the oldest dwarven delvings after its reclamation by a band of adventurers, the history presented below was found literally written on the walls. The dwarves had crafted the story of the discovery of natural ioun stones and creation of the artificial stones into the very stonework of the place.
This supplement has includes:
Creator of the Ioun Stones
Variant Rules: Ioun Stone Orbits
Variant Rules: Mounted Ioun Stones
New Feats: Ioun Attack, Ioun Control, Ioun Defense, Ioun Mastery, Ioun Sacrifice and Strike Ioun Stone
New Magic Items: Ioun Eggs, Ioun Staff, Rare Ioun Stones
New Spells: Steal Ioun Stone and Shatter Ioun Stone
New Monster: Ioun Elemental (Variant Earth Elemental)