Books of Knowledge

Books of Knowledge are the rarest perception rewards, they are consumable items that grant skill points upon consumption.
 * Brown Book of Knowledge - grants 5 skill points
 * Grey Book of Knowledge - grants 10 skill points
 * Green Book of Knowledge - grants 20 skill points
 * Blue Book of Knowledge - grants 40 skill points
 * Purple Book of Knowledge - grants 80 skill points
 * Orange Book of Knowledge - grants 160 skill points