Fighting in a group was something that Brennan had not the opportunity to do in a long time, so very long of a time. Despite his practiced focus, his memories betrayed him - recalling flashes of the night that his home was destroyed. He shook his head irritably to clear it, tossing his hair into disarray as a result before brushing it back out of his eyes. It would be unfortunate if he was skewered by an enemy because his hair blocked his view. Knowing his luck, and his hair, it was probably exactly how he would make his exit.
Until then, he would at least try to go out fighting.
He inscribed a glyph of repulsion below him, after making sure that there was no one around him. That set, he began casting. It did not matter to him if who he was fighting was man or beast, it only mattered that they were the enemy and needed to be dealt with as such. While it may have been an overly simplistic way of thinking, it was also uncannily effective. When all other concerns fell away, and the fight was between himself and his target, then he was at his best. Needless to say, this mindset was not given to defense of self - much less others. Back home, that was far less of a concern, being as those he fought beside could handle their own and then some. Here it would likely come into play, as a larger portion of the population was incapable of fighting. But that was logic, and it did not settle down easily in his mind.
Instead, he would rather focus on the fire that bloomed from his outstretched hands, and on the play of the flames as they licked at the Darkspawn's corrupted flesh. The smell was sickening, but his stomach turned over not out of revulsion, but in excitement. It had also been too long since he had last let loose. The constraints of staying in hiding had chafed for far too long. Tossing them off was a relief and a joy.