Appearance
The cover is composed of three heavily-hinged cast-iron panels with a thick Bruthem-Leather interior-lining. A sculpted lock in the form of a grotesquely leering pseudo-satyr bars access to the Treatise by any impudent would-be perusers incapable of overcoming a simple Lock spell.
It is rumored that the lock attempts to bite anyone attempting to open the Treatise by any other means, or if their attempt to overcome the Lock spell fails. It is rumored that the thing's bite might be poisonous, vampiric or both...or something worse.
The entire Treatise weighs just over 800 pounds and is roughly 1' by 3/4' by 11" thick. It has 150 hit-points, is immune to acid, fire and most forms of corrosion, and it permanently radiates a Triple-Shadow.
[Treatise of the Three Spheres; Level 6, INT 17, EGO 21, AC 3, HP 150, ---]
Known Risks
Heavy, awkward and has a tendency to increase in encumbrance over time when carried about. Initiative is reduced by -1, Encumbrance is doubled and/or Movement is halved, and all healing takes twice as long as normal for anyone involved in transporting the Treatise. This effect is well documented, so few who are in the know ever attempt to move the Treatise and most scholars will insist on studying it right where it was found, which can often lead to all manner of headaches and trouble for those involved in keeping said scholars safe and undisturbed.
Despite being extremely troublesome to move, the Treatise has a tendency to disappear from wherever it has been located after 1d4 days despite any and every effort to anchor it or keep in from shifting to a new location.
Suspected Rewards
The Treatise is the only known/recorded source for the means to gain access (Attunement or otherwise) to a set of three Otherplanar Regions listed as Allrakallim, Ruttillon, and Vattej. No one is quite sure if these are distinct Planes unto themselves, or sub-regions of some obscure plane(s), or something else like perhaps some sort of nested or linked set or Demiplanes.
Anyone able to settle the academic disputes and scholarly conjecture surrounding this rare tome might find themselves faced with quite a good deal of acclaim and recognition within those rarefied circles that ponder and obsess over such matters...and no doubt gain a few enemies as well since providing definitive facts often tend to explode pet theories and can derail careers built upon opinion and conjecture based solely on second-hand accounts...
Notes
The Treatise is completely impervious to all known forms of Divination and all Location Determining spells...as are anyone directly involved in the study of the text for as long as they keep reading.
So far no one authority agrees as to what language(s) were used in the transcribing of this Treatise. Few have ever been able to get very far in studying the thing without recourse to one or more spells.
The first actual spell encountered in the Treatise appears to be some sort of Summoning that draws the attention of 3d6 Thysanurians for some reason...and failure to decipher/translate this spell seems to prevent would-be readers progressing any further. Successfully copying the spell is a complicated and time-consuming process that more often than not takes longer than the time allowed, for this reason some impatient academics have resorted to simply casting the summons and hoping their hired mercenaries and defenders can handle the onslaught of Thysanurians while they attempt to delve deeper into the mysteries of this cryptic Treatise. So far most such attempts for which there are any surviving records seem to have failed for one reason or another...