The signature weapon of [Yareli] meets the powers of the Void, and yields impressive results.

First, let's look at some of the DOWNSIDES of [Kompressa], as this is important information that will help better understand why a simple Arcane has changed everything for this weapon.

Base stats:
2 Viral damage per projectile (direct hit)
42 Viral damage per projectile (AoE) with falloff
6% Critical Chance

So as you can see, this weapon was not designed with damage in mind. Having an AoE means [Galvanized Shot] will be useless for roughly 95% of the weapon's power. Having such low Crit Chance means even less capability of performance, as you'll only be firing white bullets for the vast majority of your onslaught.

Before we gained Cascadia Empowered, [Kompressa] was nothing more than a cutesy primer that could offer max 3 elements without Warframe ability influence. Even an unmodded [Kuva Nukor] could do that. This led to the [Kompressa] being leveled for MR and shelved by those players who even bothered to farm it (or in my case, pay the plat to avoid the farm).

Now, let's look at some of [Kompressa] 's highlights, specifically those that shine with Cascadia Empowered:

Base stats:
4.0 Multishot (this means a rapid boost in pellet counts with ANY Multishot resource)
3.33 Fire Rate (respectable number, still puts 12 pellets out per second minimum)
30% Status Chance (combined with the MS and FR stats, even unmodded this weapon could max Viral stacks very quickly)
Innate Viral, to boost damage by up to 425%

This weapon's best qualities are an excellent match for Cascadia Empowered, as the Arcane only damages through status procs, and aside from Faction modifiers, the damage is unaffected by mods directly. Indirectly, by boosting MS, FR and SC, you increase the amount of status procs dealt, and every single proc will trigger the Arcane, and the Viral procs will quadruple the damage.

On this build, your flex slot would be Primed Quickdraw. A few other acceptable options in place of this mod would be:

Primed Fulmination -- the AoE on [Kompressa] is pretty small, so even a slight boost to this would help deal with enemies who are clustered together.

Anemic Agility -- as previously stated, more FR means more chances to proc quicker. If you are using Arcane Velocity, This would not be an ideal choice.

Primed Slip Magazine -- I'd only actually recommend this if you don't have [Primed Quickdraw]. Cutting your Reload Speed almost in half would have a better uptime than extending your magazine by only just above half.

Riven -- everyone loves their purple cards. The optimal stats would have course be FR MS SC and something harmless (Zoom, Recoil, or even Critical Damage; remember, the Arcane is doing all the work here).

If you're curious of the math behind this setup, let's review some numbers.

+290% Multishot comes out to 15.6 pellets (let's go with 15 for the math; and direct hits account for two instances of proc opportunity since it has AoE)
+60% Fire Rate comes out to 5.33 shots/second (we'll round down to 5)
+270% Status Chance comes out to 111% per hit (we'll round down to 100%)

30 procs per shot (15 shots, 15 pops, all 100% SC) x 5 shots per second = 150 procs per second
150 procs per second x 750 damage per proc = 112,500 damage per second
112,500 x 1.55 from Primed Faction = >174k per second

Then factor in the Viral damage boost by x4.25, and you're looking at over 740k raw damage per second (before applying weakness and resistance).

While this certainly would not be a recommended weapon for level cap endurance runs, Cascadia Empowered has given Kompressa exactly what it needs to be more than useful in general gameplay, and even some short-term endurance.