First a full explanation so everyone knows what I'm talking about. Thus this will sounds more like a wiki article or review at first.
This is one of about four weapons added with Legacy of Romulus. They're gotten in commons from Mark 1 up to Mark 9 from the ground weapon vendors in Romulan Flotilla and New Romulus Command. The Dilithium Store carries Rares from about Mark 5 through to Mark 10, and Very Rares of Mark 11. They do not drop from enemies at all, and there are no 'Romulan Plasma' variants of any of the four weapons in the rep store currently.
This weapon, like two others of the four(The exception is the Long-Range Plasma Assault Minigun-just like your regular miniguns, but with a 35-meter range rather than the standard 30), uses a Plasma Energy 'ammo' system. When it's empty, certain moves of the weapon(Usually the secondary) cannot be used. It takes 22 seconds to charge to full from empty. You may of course fire any attacks that use ammo at any point between full and empty as need be. Plasma Energy does NOT recover if you switch weapons-the weapon must be active to charge.
The standard attack is a single-target bolt. Nothing special, except for the high damage(The Purple gives a tooltip of 74 or so. Bear in mind there's no real cooldown on the shots) and the fact that this attack costs ammo. I'll get to this.
The secondary attack is a chargable bolt. You hold the button to build up energy(Maximum charge time is about four seconds, but you can hold the charge indefinitely unless you don't have the ammo for a full charge, in which case it fires when it hits the maximum you can fire-yes, you can pre-charge and walk around with it, but you'll be moving slower), then release to fire. The blast can hit up to five targets around whoever you hit. This can take up to 80% of your ammo. The damage can be considered worth it. There is a proc effect on this attack-up to 15% chance to take the target's shields(If it has any) offline, based on how long it was charged. There is a 4-5 second cooldown between shots of this secondary.
Neither of these attacks can Expose or Exploit. I presume due to the sheer damage output it has already.
My issue is with the primary attack costing ammo. None of the other ammo-users do so with their primary attacks. This combines with the secondary eating much ammo. You are guaranteed to run out of ammo during battle. It may be quick if you use the secondary, it may be slow if you restrain yourself to the primary attack. But it WILL happen. And you cannot switch for a time, let it recharge, then switch back, as you might expect. And there are a decent number of enemies that will eat a full salvo(In any combination of primary and secondary) from this weapon and live. Leaving you with a paperweight.
It would be nice if ammo could recharge whilst the weapon were in the secondary slot. Either that or the primary attack could not cost ammo.
INTERESTING! I didn't realize they took ammo, I thought it was a 'timed energy buildup' thing. I noticed these too and tried them when RoL came live. They're nice but I've since switched back to my favorite type: http://sto.gamepedia.com/Pulsewave_Assault
I like the knock back feature especially with the 'secondary shot' which usually affects more than one mob - especially if you do it just right! I go with the phaser or plasma while at least one of my BOff's will go with tetryon type. Phaser for stun & -run speed, plasma for DoT and tetryon for -shields.