Colonel Mael Radec is the final boss of KZ2 and he proves to be quite a challenge, but with the right tactics you can kill him in one try.
Some walkthroughs may say to knife him dead, but the STA52 is a much better option. Shoot him from a range, but when he comes up close, make shure you are on the 2nd floor, where you have killed the flame-thrower Helghast and pick one up, set him alight and keep on burning him.
When he stops and you're out of ammo, he may teleport away to the other side, but on the second floor there are some VC32 sniper rifles. Pick one up and shoot him.
This isn't completely foolproof, but it is an effective strategy.
