Victor Crowley Becoming Invincible

Why did Victor Crowley become more and more invincible throughout the series? In the first film one bullet put him on the ground for a minute or two and now a whole SWAT team is shooting at him and he barely flinches. Personally, I found it creepier when he could be hurt and was a little more human. Also, how come Victor Crowley's face changes throughout the series? Is this just another ode to Friday the 13th like Jason's constantly changing facial features from film to film?