Melee Gauss build suitable for any content in the game save for Eidolon hunts - Including long arbitration runs. I'm usually the one ressurrecting people in Arbitration PUGs because I'm so damn immortal and the Cyath far out-damages anything apart from dedicated nuking frames, all while zooming across the map and blasting eurobeat.
The melee rework made heavy attack spam very powerful, especially on weapons with guaranteed slash procs as part of the heavy attack combo. On machetes, if you hold F to wield the weapon and hold block, you can keep doing only the first part of the heavy attack combo, which in addition to doing a lot of damage, allows you to continue running at full speed. I recommend binding heavy melee attack to mousewheel up and mousewheel down rather than clicking. Since the machetes kill things so quickly, the best way to improve your efficiency is to close the gap between groups quicker.
In addition to the sprint speed bonuses adding to [Gauss]'s already impressive speed, the melee setup allows us to run [Dispatch Overdrive], adding another +60% sprint speed, and [Amalgam Serration] adds another +25%.
Max duration adds some truly massive increase to your melee speed with Redline, as well as great tankiness and free melee damage and staggers with Kinetic Plating. Tapping Mach [Rush] allows you to easily fill up your battery and activate Redline.
Thermal Sunder can strip armor, but honestly, you won't be standing in one place long enough or fighting enemies that live long enough to merit ever doing so, especially since you mainly deal slash damage.
[Redirection] synergizes well with the [Regen] from [Gauss]'s battery passive. Arcane Aegis allows you to make use of that [Regen] while under continual fire. For the other arcane slot, I use Arcane Pulse, which synergizes well with [Synth Deconstruct] and [Synth Fiber] on my sentinel to provide some healing to defense targets and the sentinel.
Using the [Cyath] Zaw [Machete] lets us use Exodia Brave for free energy, which works with [Quick Thinking] and [Primed Flow] to [Protect] against damage that penetrates shields. Kinetic Plating also gives you immunity to staggers, which negates the main downside with [Quick Thinking].
The only enemy type that's really a challenge with this build are the sentients, and since we need a primary weapon anyway to act as an Amalgam Serration stat-stick, we can use a max fire-rate [Shedu] to strip sentient defences. Running no secondary allows you to easily change between the [Shedu] and the [Cyath] while fighting, without breaking the [Flow] of combat.
If you want to go max speed meme, you can slot in Speed Drift and Coaction Drift, especially with the changes to shields, though dropping Quick Thinking/[Primed Flow] would leave you vulnerable to toxin. This could be counteracted with Arcane Resistance, or some combination of [Vitality], replacing [Redirection] with [Primed Vigor], or slotting in [Life Strike] on the weapon, but in my experience the minor speed increase wouldn't be worth the hassle. You'll aready be bonking into walls plenty with how fast we're going. You could also slot in Arcane Phantasm for a more substantial speed boost, if you don't mind the hassle pausing your murder to get parries to keeping it active.
Melee: Melee Gauss's Spinblade Cyath
Primary: Sentient Stripper Shedu
Sentinel: Helios Prime
Sentinel weapon: 368.7% status Cryotra
Sentinel weapon alternative: Rad and Viral Helstrum
Sentinel weapon alternative2: Rad and Viral Deconstructor
Recommended soundtrack: Your choice of The Initial D OST, City Escape, Snailchan Adventure or the Beyblade theme.