We'll require you send us isolated stem files [preferably in a high-quality .wav format] for mixing. Please send two versions of your session; one with all effects and all with zero effects - this gives us a feel for your vision.
Assuming that your mixer has done a stellar job, please arrange to send us a final .wav mix for us to master. Reference bands, songs etc are required. Otherwise we'll make your metal band sound like Bjork.
You're stuck with your song and need some help, right? We can offer mere guidance, perform on your track and much more. See this page for more details.