"Receive the highest rating on a Legend on Nightmare difficulty" is an emblem achievement found in the multiplayer portion of the RAGE game. I cannot find any information on what are the requirements in order to obtain this emblem.

Can someone tell me what is the rating required for this emblem and what are the steps I need to perform in order to obtain that rating?

Really need help with this one. If anyone can provide information I would really appreciate it.

I was finally able to get this emblem. It appears it is strictly dependent on the score you achieve. In other words you don't have to have x number of head shots, x number of assists, x number of multi-kills. The score you need to obtain the emblem is above 6000. In order to get that kind of a score you will need to perform mostly head shots, have a fair number of brutal or multi-kills. My recommendation is to try and get this emblem on Unwanted Guests. This is by far the easiest Wasteland Legend mission on Nightmare. You can get a fair number of brutal or multi-kills by using the Rocket Launcher. There is some extra HE Rockets in one of the rooms in a sink (consult a walkthrough if you cannot find them). There are also two set of Pop Rockets (a total of 12) although they aren't as effective on Nightmare (consult a walkthrough if you cannot find them).