This Trophy requires patience, practice and persistence.
The goal is to complete the gauntlet in 33,65 seconds or less while hitting all 15 guys. For each guy you miss you get a 2 second penalty - so don't miss!
Basic loadout:
Primary: EVA-8 Auto - Less accuracy required
Secondary: Doesn't matter
Grenade: Arc Grenade - Splash damage and explode on impact
I recommend playing through the campaign on master (for the Trophy) to get used to controls and wall running before but it can be done whenever through Chapter Select after you've gone through the tutorial - although if you're good you can get it first time playing it already.
Before shooting the guys, learn to run the route flawlessly in the required time and then incorporate shooting and throwing grenades.
If you use the EVA-8 Auto you only have 1 extra shot before you can reload so go for 1 shot 1 kill to be safe.