I probably spent 3 hours total trying to beat Scorpion with Sub-Zero and I got close too. But its when I went back to the map, restarted the mission a few times and got Nightwolf that my chances of beating Scorpion went way up. Using Nightwolf, it only took me about ten tries until I finally figured out the best tactic. Like he said earlier, it's all about the shoulder bash. After that, get some distance between you and Scorp and launch a barrage of arrows at him, he'll get hit by almost every one. If he gets close, shoulder bash him again and repeat the process. Do multiiple shoulder bashes if you have to (it has a quick recovery time),whatever knocks him down. If you're feeling risky, you can throw in a lightning bolt after he falls down but make sure he doesn't roll to the side, or you're left open. Oh yeah, be sure to block efectively too, as he will teleport kick you or try to spear you. Stay moving so you can evade his unblockable flame attack.