Tome of Demonic Lore (3.5e Equipment)
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Tome of Demonic Lore:: This disproportionately heavy codex (bound in the tough membranes of an Imp’s wings) is a truly colossal volume of raw demonic lore; by perusing its pages for 8 hours per day for a week, and for at least 8 hours every week therafter, a character may be granted a constant +5 bonus to Knowledge checks involving demons. Further, by searching through the book for 2 full round actions, the reader can find the relevant section on a given subject, resulting in an immediate additional +1 bonus to his check (the check must be made in the reader's next turn).
Faint divination;CL 6; Craft Wondrous Item, deamoncall; Market Price: 9,000 gp