That's correct. Reason magic tends to be more common because it's easier to master, and the risks that come with it are a bit easier to control. Dark magic is a bit of an anomaly, from what I understand; it is calling on something more ancient and unpredictable than typical black magic. Some of the highest level dark magic spells can rip the caster apart if they aren't able to control it, while black magic tends to cast outward, creating explosions.

[He says all of this like this is a totally normal conversation and not at all horrifying. But really, are you surprised??]

Dark magic requires more focus than most reason magic. It needs to be drawn from within. Think of it as harnessing the darkest corners of your mind; it's the best description I have. The texts will explain it better than I can. I've always had more of an aptitude for dark magic than black magic, so it's a bit difficult to explain.

[He could cast Fire while he was a Mage?? But he's moved on to Dark Mage so he's back to his preferred dark magic attacks. It comes naturally now, and he scarcely remembers a time when it didn't.]