I agree this sound effect added to power would be nice, but that background noise is strong on some parts of file. Sound effect could be added, but problem in my opinion is quality of it. There are also parts (breaths, screams) which should be eliminated in order to get beter sound effect, but with croping of those parts, sound file will be degradated in great way. I won't like to hear witch king's scream or orc/human breath when I use this power, that would kill my experience in game.
I am just refering on possible problems because I have experience with sound files and processing (e.g I have created Erebor horn sound from movie audio which was with great noise). In my opinion processing of this file will only degradate its quality, and adding that sound effect in its source patern is not appropriate because of its quality (again in my opinion).
Regards,
CragLord