Q: What are masterwork rolls?
A: Most legendary weapons are capable of being Masterworked. The masterwork system is a way for you to upgrade your favorite weapons to their maximum potential.
Q: What does it take to upgrade a weapon to a masterwork?
A: Upgrading your weapons, in broad terms, takes a small amount of glimmer, legendary shards, and, most importantly, Enhancement Cores.
Depending on what Tier your weapon is at, the requirements to raise it to the next tier increase the closer the weapon is to being fully masterworked (Tier 10).
Q: What benefits do I get for masterworking a weapon?
A: Each tier that you increase your weapon will grant a small buff to a single stat, chosen randomly when the item drops.
Beyond that, at Tier 5 you gain access to a kill tracker. At Tier 10, your multi-kills will generate orbs of light.
Q: So what are these "masterwork roll" stats?
A: These are the possible stats that upgrading your weapon will grant a bonus to. Depending on what tier you are at, you can grant anywhere from 1-10 additional points in any of the stats listed to your weapon.
Q: Any catch with this?
A: The Bungie API currently says that all weapons can potentially roll with all stats as their masterwork stat. This obviously isn't accurate, as Blast Radius isn't applicable to, say, Auto Rifles.
The list you see on this page is trimmed to only show stats that actually appear on the weapon. However, it is possible that Bungie has additional logic behind the scenes that further filters these
possibilities to, for example, prevent certain items from being able to have an Impact masterwork. Until Bungie modifies the API files to 100% accurately display which masterwork stats are possible on
each item, take what you see here with a pinch of salt.
In PvE, this perk is great despite being so underappreciated - it just requires you to do some micromanagement. Obviously, it'll activate when you're surrounded by trash mobs - hence the perk's name - giving you a much better chance of surviving in any occasion you get mobbed by a sizeable group, or letting you dive into a big group and kill them quickly (i.e Gambit). However, it can also be a powerful perk to do boss DPS with - you just have to figure out how to keep it activated without dying or accidentally killing any enemies you're keeping alive to have the damage bonus. If you have some means of tanking damage, like a Well or a Barricade, you can sit in the middle of a group of mobs and shoot up at a boss while they try, but (hopefully) fail, to kill you. Just maybe don't mind the flinch. Also, it's not really on many *good* Heavy weapons, so despite the monstrous damage bonus, you might not outdamage a Taipan or Catyclysmic.
In PvP, this perk sees less usage because of the already-inherent dangers of trying to activate this perk deliberately (as opposed to letting it activate when enemies come to you first) becoming much higher. Just one enemy player can kill you in a second, and trying to initiate a 2v1 (with you as the "1") without an overshield or Special/Heavy ammo is incredibly deadly, so it goes without saying that running in the middle of *three* enemy players at once is near-suicide. If you can pull it off, though, it's surprisingly worth it, because again, you get a higher damage bonus than even max-stack Rampage or Swashbuckler. No weapon benefits from this playstyle more than the Aggressive Solar Glaive, Judgement of Kelgorath, as Enhanced Surrounded causes its shots to kill in *one hit* within effective range. Get the drop on the enemy team, and you'll kill way more of them than you should be able to at worst, or maybe get a team wipe at best. The only problem here is that Surrounded is in the same slot as Kelgorath's (for-now-)unique Close to Melee trait, which is also kind of a big deal, and more popular to boot. I'd forgive you if you actually craft two of them just to have Surrounded on one and CtM on the other.