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.