[quote=Toxic Diamond]
I'm talking about the dark mageblood.
[/quote]

It's the same as any Mageblood which extreme emotions or stressful events can cause a student's magic to wake up. The magic mechanics in the CS explains it a bit: 

[quote]All Races within Tiien have mages, the percent different between each one, and each individual is able to manipulate one Mage Blood. The Arcanite within each individual is as unique as their blood, without it they are unable to manipulate Tiien’s magic or even live. Mage Blood in particular is a concentrated source of Arcanite, and nearly 50% of the blood which diminishes whenever one uses his/her magic. Now not all those able to perform magic learn to become mages or possibly ever realize they have such a gift throughout their whole lives. Usually magic is discovered through stressful events or emotional trauma resulting in either a lack of control or minor spark in magic. However it’s possible for magic to fade from an individual if not regularly used over long periods of time, unique in each individual, but rarer cases have been known to cause the opposite. Instead of losing their ability, there’s a sudden magical spark that soon grows out of control on their own due to the novice’s inability to control them. With these mages it’s required they seek training in hopes to learn to control their magic or risk one day falling victim to ‘Blood Sickness’. [/quote]

If you mean the alignment, Student must learn how to first control their novice decay and increase it's power until Gray, the Nox teacher, sets up a trip to Craggville which is home to Aarem's Cragg. The Cragg is basically a crack in Tiien that is endless and more akin to a beehive with tunnels that lead down, filled with Aarem's little...experiments, far worse then the Syphis. Students must navigate their way down, each one divided into either a Guide or Warrior role depending on what each Player wants and each have their pros and cons. However both must work together if they want to make it out alive. Once they reach the center, the Nox itself, there's a tower were the final confrontation happens and all students that arrive must face. Afterwards you're allow to align with one of the three Nox sections.