Vaerendroon

Vaerendroon was a skilled wizard and sage of magical lore who lived during the mid–14 century DR.

History
He was known to trade magic for specific spell that he was eager to possess. He often dealt with apprentices of other powerful mages in order to gain access to unique spells. Vaerendroon compiled his collected knowledge within a tome called Vaerendroon's Ineffable Enchantments and sold the volume for 90,000 gp in Baldur's Gate when he needed coin badly.