A Hack n' Slash, Hit n' Run, and super fun build.

[Gauss]'s Redline is ingrained in all of his abilities, effectively making it the most important. Redline can give insane multipliers -especially to melee, as it grants an attack speed buff along with a melee damage buff (via Kinetic Plating)-, and its buffs scale with duration. That being the case, this build will focus on max duration. Meaning if all goes well, you'll be Redlined semi-permanently with a sweet >300% duration, and all the better for it.

I'll be listing why I picked each mod:

• Narrow minded: Main Redline buffer
• Primed Continuity: Redline buffer
• [Constitution]: Redline buffer + [Gauss] is especially weakened when knocked down (As he must constantly be on the move to be effective), so some extra insurance can't hurt.
• Augur Message: Redline buffer + slight shield support. (interchangeable. Fortitude is a good option).
• [Primed Flow]: [Gauss] will constantly be using his abilities, so he'll need the energy to keep up. Synergizes well with Kinetic Plating to provide a reliable source of energy.
• [Redirection]: Every frame needs at least one defensive mod to be universally viable. [Gauss]'s passive synergizes with shields, so it has higher priority than health or armor. And as [Gauss] should be constantly on the move, he'll regenerate shields before he loses them. (There's no need to worry about status procs because of Fire Walker)
• Adaption: Synergizes really well with Kinetic Plating, and will lower the amount of battery lost. (Kinetic Plating loses less battery the weaker the attack is, and Adaption is calculated before Kinetic Plating). Kinetic plating + Adaption can give almost full damage nullification (with Redline inactive).
• [Streamline]: Allows for consistent gameplay.

Fire Walker: This ability covers for [Gauss]'s biggest weakness; status procs. Fact of the matter is, even when [Gauss] reaches 100% damage mitigation to IPS, heat, cold, and blast damage (100% battery + Kinetic Plating), he is still very vulnerable to status procs, as they go through armor and shields (he's not as vulnerable to damage types he doesn't gain mitigation against, as those still need to go through his shields). Even better is that Fire Walker is mainly reliant on ability duration (which this build focuses on), and matches duration times with both Kinetic Plating and Redline (meaning that there's no need to keep track of durations). It also makes up for taking the place of Thermal Sunder by providing it's own crowd control. Enemies that touch the flames left by Fire Walker get procced by heat, and stagger. And of course, there's the basic effect of giving the fastest frame even more speed.
(Chosen over Thermal Sunder as that is effected negatively affected by low ability range -which is needed for extremely high duration-, and because doesn't get many benefits from ability duration.)

Aura and Exlius:
These depend mainly on playstyle and are interchangeable, but here are the ones that are generally best on melee Gauss (In order of effectiveness -imo-):

• Aura: Swift momentum, Corrosive Projection, Steel Charge, Energy Siphon, Sprint Boost.
• Exlius: Rush, Speed Drift, Primed Sure Footed, Preparation Handspring, Coaction Drift, Cunning Drift.

Please give your commentary/criticism/suggestions/experience s with/on this build! Your feedback is appreciated!