Magic users are able to tap into one of 8 elements via Statux and Strabis, or Black and White magic. Summoning too much of either magic can have fatal side effects, as Khon has taught in Chapter 3.
Magic users rely on Klenots, or the smaller Ken, to channel their magic through their body and out into the world. The Dragon Laska are bestowed with very special Klenots that can handle huge amounts of magic. With the proper training magic users can summon their powers near instantly, but it's possible they can put themselves in a lot of danger if they don't channel properly.
When a user takes in too much Strabis their body enters the state of Mystion, where the body forces all magic out to try and purge the imbalance. This can cause magic explosions and leaves the user without any magic for sometime, if they survive.
On the other hand, taking in too much Statux can lead to Estion. Where Mystion lasts a few seconds, Estion can stay in a user's body for the rest of their life. It slowly eats at their Strabis, taking over with each spell they cast. When there's no Strabis left the user is at the whim of their Estion.