Axlerowes, interesting plot idea, I may try to work it up into a scenario someday.
sverigesson, they took the updated strain of horses, the battlesteeds, and continued to refine them. Somehow, along the way, they discovered that the battlesteeds were different from regular horses. I can see a young Catfolk archer or something who starts to get the idea that his horse is trying to tell him something. Perhaps the Catfolk is also a bit of an empath and he realizes that it really *is* trying to communicate with him. A story there, I am sure.
As it is right now, it is mostly a list of names and unbeatable superpowers. Not much use as it is. I would try giving each one a 2 or 3 paragraph backstory to say how he came to be that way and how he uses his powers. Try to include things about why he is that way. My players *love* to do an end-run on me and convert or otherwise neutralize my badguy. I think they like that even better than taking him down. You don't want that to be easy (unless it is part of a continuing scenario-arc), but if they discover that it is possible, they will try really hard to make it happen, with all kinds of roleplaying stuff going on, and everyone has fun.
Also, be sure that he is not too powerful. Of course, that depends on the power level of your players, but a samurai that removes 95% of a hero's health in one shot is pretty damn powerful. Or the rat that can not be harmed- arm him with a knitting needle and he'd eventually be able to kill anyone. Or the hunter with a powerful gun that always rolls criticals?
To my way of thinking, a villain should be 1) very hard to take down, 2) do enough damage to make the hero worry, and 3) have some weakness that can be discovered through roleplaying and/or research. In my experience, an unstoppable villain, or one with a blow-them-away attack will not be any fun for your gamers. They want a challenge, not an unstoppable tank or a Monty Python rinky-dink.