I wasnt planning on making him able to use magic of that level forever. He's powered by a god, so he's pretty good at it, but because its not a perfect unison, after a while, Stribog has a hard time actually puppeting Khold's body, and if he uses too much power, his body will shut down until Stribog basically rewires everything. I was thinking that the synchro rate would get better and they'd be able to use power more efficiently, rather than his abilities getting better, cause I think they're definitely strong enough as it is.