Some concept art of James in his Asura form. It's something akin to a spider symbolizing his contract with Astrid (which he REALLY wants to be free from). When he uses his Asura powers, something of an exoskeleton or armor will form around him. Then he will fly into a berserker rage, becoming nearly unstoppable and almost out of control. In this state, he is just as much a danger to himself and his allies as well as his enemies.

Because of how destructive this power is and price he paid and the guilt that weighs on him, he prefers not to rely on it.

This is still in concept so I may change a few things after I explore the idea a bit further. But I do like the idea that a contract he struck with Astrid ultimately came at a cost of his humanity.