The sheer amount of magic in Ryn's body is nigh-unprecedented in humans. It's the result of a malformation of his aura which forces it to strengthen way beyond what it was supposed to, and it's slowly killing him. Ryn can only consciously use a fraction of his actual power, and even that's very painful. The more he uses, the more it hurts him.
Human mages have a handy inbuilt response where their magical abilities are heightened during moments of extreme stress. Except, for Ryn, this isn't handy at all — when powers as vast as his are released, it's uncontrollable and violent. As such, Ryn has to wear sealing devices on both wrists which constantly suppress his magic. They make it so that his magic can't manifest, but unfortunately they don't do anything to mitigate the breathtaking agony and other ill effects of a surge (weakness, nausea, migraine, vertigo, some other nasty stuff). Unsealed, his uncontrolled magic could level a building.
Ryn's presence is amazingly conspicuous — in the same way a grizzly car accident is. His aura is so vast and so malformed that even people without much magical ability can perceive it on an unconscious level.
Ryn can appear to summon flames out of nothing, which can sit comfortably on his skin or clothes without burning him. Be careful though, they’ll hurt you just like real fire.
Ryn can effectively make himself into a terribly inefficient space heater/cooler. And if he holds something in his hand, he can heat it up/cool it down.
Ryn can appear to produce immense electrical charges on or near him. He can make electricity arc between his fingers or arms, which is cool, and scary as anything. It’s as dangerous as it looks, too.
Ryn can also output a substantial amount of random electromagnetic interference. He’s only managed to do this accidentally so far. He’s capable of disrupting Wi-Fi, Bluetooth, radio, TV and other such signals; making lighting flicker, forcing computers to restart. That kinda thing. Kinda spooky.