This build is paired with a gunblade running the 3 melee gladiator mods, which is why it uses [Gladiator Aegis].

Quick build breakdown:
Elude isn't as slow as you might think it is, in terms of eroding restraint. It only takes a few seconds and you're in business. The main reason for Elude over Lull is because of Warcry. If we are to go for Lull, that ability wants 40% or even 13% duration, which at that point gives us 6 seconds and about 2 seconds respectively. That's way too little, even with Eternal War. This build easily sustains [Serene Storm], and has monstrous attack speed and survivability.

So how do you play it?
Step 1: cast 1 and 3, then wait for enemies to erode your restraint. Step 2: cast 4 and then 2, to give monstrous melee attack speed and enemy slowdown. If you're in a group, the attack speed applies to allies as well. Eternal War, the augment for warcry, means that whenever we get a kill with melee (this includes the waves) Warcry is extended by 2 seconds, with no cap on how many times it can get extended (As far as I've tested). Theoretically, this means infinite warcry. If you maintain low restraint enough for [Serene Storm] to last as long as you want, so will Warcry. Which of course, gives 135% attack speed, which is quite amazing.

What mods could I replace?/ What could I improve?
Augur Secrets can be dropped for Rolling Guard or another mod if you want to do that. I wouldn't replace Streamline; if you do, Elude can really tear through energy.

If you want to improve this build with forma, it is very easy. Place a naramon over Streamline so that you can use Fleeting Expertise in other builds.

Then you have two choices:
Either A, place a forma over Reactive Storm because that mod is mandatory anyways, and you can run Power Drift at that point with 1 extra mod capacity to spare.
Or B, use an Aura Forma and run Steel Charge, and then place Power Drift, which again leaves 1 extra capacity.

Both options use 2 forma total.

Another option is to use 1 forma on a Madurai, replacing Umbral Intensify for Transient Fortitude. I know I said -duration is bad, but with the mod on it's still 11 seconds which is totally fine.

What arcanes could I use?
I use two melee arcanes, but you could replace Arcane Strike for Molt Augmented if you want.

What subsume should I use?
This is a warcry centric build. That's the reason behind elude, no Fleeting Expertise, and no Transient Fortitude. I have so far tested Terrify, Pull, and Airburst, and wasn't happy with any of those. However if you do want to use a different subsume, put that ability over Elude and keep Lull, then run the two mods I mentioned earlier to be able to spam Lull.