Amnesia Trailer : Grunt attack music?

[Zaari]

Are you referring to att_grunt.ogg being too subtle? If not, then find att_grunt.ogg in Amnesia - The Dark Descent\redist\music. If you are, then there doesn't seem to be any way to obtain that track unfortunately. What you are hearing in the teaser trailer is the original soundtrack that has since been taken out and revised before Amnesia's release. The only remaining raw file of the track is most likely either scrapped from existence or is still among the FG staff.