Wondrous Item (tome) , Legendary (multiple)
Wensharian wizards, collaborating with the High Eladrin of xxx, fused the secrets of elven high magic with the scientific principles of astral ambiance and created Astral Tomes containing legendary and epic arcane mysteries.
These tomes contain the peak knowledge of the Wensharian Empire and if studied grant abilities and knowledge into some of the innermost secrets of the cosmos.
i.e. studying one tome might grant a permanent +2 to +5 to spell attacks/DCS, or teach an epic 10th level spells.
For those of insufficient power to handle the knowledge contained within, there is a risk of serious mishap, accident, or even death.