Are we talking about type of magic here??
Well, i have another idea about how magic choice is..
The point is freedom..
1. There are some Basic Magic that has some requirement of principle. something like fireball, blizzard, time stop, warp, teleport,
2. There are some Advanced Magic that has some requirement of principleS. something like InnerBurn (Increase entropy inside creature and damage them with fire.. - kinda combination of entrophy and elemental)
3. There are some CUSTOM MAGIC..
this custom magic is kinda pick from basic magic and we kinda give some Strength to those magic.