So first my item, then my thought process on it.
Codex of Cognitive Superiority
Aura Moderate Transmutation; CL 11th
Slot none; Price 40,000 gp; Weight 5 lbs.
Description
A large, weathered book filled with strange, often indecipherable discussion on various areas of knowledge. The Codex also contains sporadic journal entries from random people about life experiences ranging from love, adventures and a variety of other events. Though seemingly having only one hundred or so pages, the amount of viewable pages within the book is infinite.
This book contains knowledge from virtually every discipline known in the multiverse ready to be absorbed, yet with a cost. To be effective, the user must spend at least one hour truthfully recording any aspect of their life ranging from instructing the reader on a specific topic to the retelling of events or actions. Any false recounting in these journal entries immediately disappears from the page.
Upon completion, the user may select one skill, attack or save which the book immediately turns to the pages relating to that skill. For 24 hours after reading these entries they gain a +20 competence bonus on a single roll of their choice for the previously chosen skill, attack or save. After this roll the knowledge gleaned from the Codex becomes lost to the user. For the next 12 hours, their mind is clouded with the memories of knowledge gained and lost intermingling with their own memories and gain no benefit from the ability bonus of the associated ability score used in the roll.
While anyone can find the random journal entries from past users within the book and read them without attempting to gain the magical bonus, readers can never again find their own entries within the book.
Construction
Requirements Craft Wonderous Item, Legend Lore, able to cast any Ability bonus spell; Cost 20,000 gp
So, when I look at magic items, especially wonderous items, I usually try to stray from "mechanical" items. Items that replicate spells, or just give static bonuses. They are fairly boring to me. In this I wanted to create something fun for both the player and the DM.
I really struggled with the bonus it gives. I knew +20 was probably high, however with only one chosen roll a day and the fact that I decided to heavily penalize the player I relaxed a bit. It felt more like an item the party would use intelligently, to plan for something specific (need infiltration use stealth, need a disguise go for it, guarantee a hit on a known tough fight coming up there you go) giving it the "This is a Hail Mary Pass" feel. The penalties I felt made it a risk to use for anything less than a last ditch effort or when the group felt that the risk was worth it. Also only disallowing the ability bonus to the skill still allowed other bonuses like feats to apply.
The next thing was the level it was intended for. If it's in the late low levels then it's a powerful item but the risk also feels a little greater requiring more thought on when to use it. At the higher levels it's still very potent, but the penalty is negligible in some cases but you're also dealing with much higher DC's so at least noticeable.
I really wanted to get across that while seemingly easy to make for the level required, I didn't want this to be an item PC's would churn out. I approached it from a 'this is plot treasure' stance. The ability to read others journal entries, not your own, appealed to me as a plot device for DM's to have fun with and create hooks, side plots or something to save their game when they have nothing for the night. Since journal entries can be related to just about anything, but MUST be truthful, PC's could view it as something reliable. In my head, I pictured the groups paladin reading an entry from hundreds of years ago from another paladin and his last stand, as the beginning of a Holy Avenger quest. A mage reading about a wizard well known for his power, and where his stash may be. Or even the groups rogue stumbling across an entry about a dragon thought long dead.
In the end I wanted the Codex to be an item that was just as much fun for the DM to play with as it was for the players to think wisely about how they chose to use it.
Thanks for reading my wall of text. TL;DR: Magic Items that can serve as future plots are far more awesome than mechanical static items.
