Chaos Magic
Since Era will introduce a new kind of magic, I thought it wouldn't be a bad idea to explain a little what I had in mind with 'chaos magic', its benefits and its dangers.
Chaos magic is like a sub-type of the whole concept of "magic". Like you have mages specialized in water magic, air magic, fire magic, etc. there are also mages who deal with the raw, untamed form of magic - chaos magic. The more common magic is tamed, structured according to formulas and spells. It's relatively safe - of course, even with common magic things can go wrong. But it's almost impossible to screw up a spell if you know what you are doing.
It's a little different with chaos magic. As already said before, chaos magic is raw, untamed magic. It has no structure, no rules, nothing. When a chaos mage uses magic, she tries to tame a small bit of this raw magic for casting her own spell. The results, however, can sometimes be quite different from what the mage had originally in mind. E.g. when wanting to cast a flame arrow, the spell can suddenly turn into a very explosive fireball, causing more damage than the mage had intended to.
Spells can also fail, even if the formula has been said correctly. It has nothing to do with the ability of the chaos mage, but rather with the unpredictability of chaos magic. Most of the times, the spell is successful, but it happens that a spell fails. When a spell fails, several things can happen. The spell can reflect itself upon the caster, instead on the target of the mage; a random incident can happen like the change of hair colour; fainting, cuts, bruises; or nothing happens.
Sometimes, however, the spell's failure is critical. At a critical failure of a spell, the mage is taken one step on the Path she walks (more about this later on). Each time she has a critical failure, she takes one more step on the Path. And that is the danger of being a chaos mage, because those Paths are dark and horrible. A chaos mage also never knows which Path she takes until the first step is taking - and even then she's often unaware of it. The reason why the Paths are dark and horrible, is because they all lead to the same thing: chaos. Sometimes literally, like with the Path of Whispering Madness, sometimes in different forms, like with the Path of Beserk Growth, where there mage turns into a tree at the final step.
Paths have been mentioned in the previous paragraph. There are in total eight different Paths. The chaos mage has no choice about which path she takes; it is randomly decided from the first moment she experiments with chaos magic. In Era's case, she has the Path of Whispering Madness, which means she will slowly turn crazy. She'll begin to hear voices, see hallucinations and things get only worse until her mind is lost to the chaos she has dabbled in for so long.
Hope that explained everything a bit. I will alter things a little from the original idea at D&D, but... it'll all come down to the same thing. Which is that Era will be crazy at the end. ^_^