Talk:Classes/@comment-80.146.10.18-20190422105318/@comment-3234315-20190425201217

This ±15% thing is for learning spells only. What exactly do you mean with "chance to hit with the extra spell"? That extra spell is treated the same way as any other spell, comparable to being equipped with spell slot number increasing items for non-specialists. The real advantage of a specialist mage (if it is one – depends on the school and the spells chosen) – is the saving throw bonus/penalty.