Book of Diplomacy

This white leather-bound book contains pertinent information about proper conduct in the presence of nobles and royalty, as well as strategies of negotiation. If you spend 24 hours spread over no more than 7 days, you become proficient in the Persuasion skill. If you are already proficient with Persuasion, you now add double your proficiency bonus to it as you now become an expert in it. If you already have expertise with Persuasion, you may add a +2 bonus to the skill. If 7 days have passed since you began reading the book and you have not finished it, you must start again. Once you fully read the book, the writing fades and does not reappear for a decade.

Notes: Proficiency: Persuasion, Communication, Social