Soldier's with improved sniper rifle and assault rifles can destroy EVERYTHING quite easily.
Ok folks, lets get started. The Soldier is the iconic Shepherd, the ultimate expression of a badass with a gun fetish. No fancy biotics or puny SMG's for you, you want to go in with your Assault Rifle (AR) blazing! But this strategy would quickly lead to your Shepherd becoming a bloodstained corpse in a doorway if your playing on Insanity. For obvious reasons, the life expectancy out of cover on insanity is somewhere between 0 and 0.
This is where the Soldiers ultimate advantage come into the fore, the ability that enables you to wipe a squad off the map in relative comfort. Adrenaline Rush my friends, is the Soldiers best friend in any situation, from a up close shotgun fight with a Krogan, to Sniping the weak points on a Mech. This ability, when used properly, will never fail to win fights. Knowing when to use it is the most important skill you need when playing on Insanity.
I personally perfer the Heightened Adrenaline Rush version of the skill, because it both increases the slowdown effect and ups the damage by 140%, which makes taking headshots with the mutishot Viper rifle both easy and amazingly effective. wearing the +10% headhsot damage helmet and updraging your sniper skills will make even Harbinger fall with just a few clips from this bad boy