I think Hades may be completely CGI or at the very least be partially CGI. The hair alone would need to be CGI because no way they could just set fire to a guy’s head.
Lord knows the only offensive magic we’ve seen them do is fireballs and beams of light…..MP’s right, I don’t think they can afford the fire hair thingie. The most they could do is give Hades a dark shade of blue hair, modeled to a similar look of the flames.
Maybe we can have a wig with the blue hair standing straight up with little LED lights threaded thru and sparkling at intervals… like when HADES gets angry… that would be fun especially since CGI would be expensive.