Use the Standard Magic User class

Sorcery
Instead of memorising spells as Mages do, Veiled Sorcerers, a branch of magic user found in the lands surrounding Xyphia, fuel their spells with their intrinsic Mana when they need it. They collect spells in a spellbook as Magic Users do, knowing the same number of spells. By casting Read Magic, they may read and transcribe Magic User spells into their spell book, removing the spell from the scroll. However, they cannot use Magic User scrolls to cast the spell. 

To cast spells, they use mana points. Sorcerers have a number of Mana points equal to their level. Each spell they cast reduces their Mana by an amount equal to the spell’s level. Thus, a 3rd level spell costs three mana points. They may cast spells of any level they know rather than be limited by the Magic-User spell level limit. They must get a night’s rest to restore their Mana points. It is said that there are magic items that can be used as Mana and even dark rituals that turn the life force of others into usable Mana. 

Veiled Sorcerers are hunted by strange creatures that feast on their stored Mana, usually by consuming their brains. Thankfully such beings are extremely rare.