This is a large AOE (61.25m radius) nuke [Banshee], sadly due to the nerf's to the augment its damage is less reliable. but for low lvl (starchart) it's still good enough for clearing enemies.

for increasing your damage you have 2 options (both can be used):
1) use sonar, to make this more viable you would swap either [Augur Reach] (drops 4's range down to 50.75m radius) or [Constitution] (higher range but sonar resets quicker) for the [Resonance] augment. You could also swap both mods off and run [Resonance] AND [Natural Talent].
2) infuse roar for a ~60% damage increase to your 4.

Your 4 always hits the torso and sonar is most likely to place weak points on the torso, which is what makes that ability combination viable but not 100% reliable (needs multiple casts of sonar, and augment for support)