He leaps back from the fire at first, a natural reaction. When he realizes it's not burning him, he uses it to his advantage. The shades are too hungry to drain him to stay back as far as they should. He uses the opportunity to attack them with everything he has.

He recognizes the effects of that spell, the look of it, and he makes efforts to let that demon live long enough to do its damage. His strength builds again, another glow of lyrium sending coruscating blue across his skin and armor. With concussive retort, another holy smite rains down and destroys the demon closest to him.

That one costs him. He visibly sags in his armor. His next few strikes are sloppier. He takes a claw rake down the shoulder that would have easily crippled him without his pauldron and spaulders. It doesn't matter. Either they kill the other two, or they're dead. Demons know no fear. Never retreat.