Originally Posted by
lemonpeace
Yeah, I just came across a couple of those panels, there doesn't appear to be any in-story reasons given establishing the nature of the ability. So far, nearest I can tell the ideas that his powers are fueled by anger and the mystical nature appear to be fan inferences from his fight with Geo-force and his (in-story) early days fighting crime with Blue Devil during the New 52. I'm still seeing what I can dig up but that appears to be what all the signs are pointing to.