Intelligence is a measure of the learning capabilities and magical power of a character, determining its memory, its ability to understand unidentified items, the intensity and cooldown of its magical spells, its ability to persuade people with logic and natural resistance to magic. It also determines the maximum value of Mana and its regeneration rate.
Reaching an Intelligence score of 20 gives the character a significant boost to Mana regeneration.
Although Intelligence is an obvious requirement for aspiring mages, it’s really unwise not to raise it to a score of at least 10 during character creation, disregarding the type of hero you’re trying to build. This is because Intelligence plays a key role in learning new abilities faster and allows a character to memorize more abilities at the same time.
Magic tricks and incantations represent the full extent of the offensive and defensive power of a sorcerer, making the increased memory given by Intelligence particularly useful. Moreover, a reliable pool of mana can make the difference between success and defeat, especially since powerful wizards usually achieve their powers sacrificing most of their physical strength.