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.
People are saying you can proc it alongside Field Prep for the rocket launcher, but the setup is a headache. The whole appeal of Field Prep is that you don't ACTUALLY have to stay crouched to take advantage, just hold it long enough to tap the reload button (or put the whole process on a macro) and get back to business. Having to actually stay crouched for 2 seconds, stand up, crouch again and reload, is some tryhard nonsense. Even if you put THAT on a macro, the additional two seconds just makes you break even with the BASE reload time. Absurd.
It's also kinda bewildering that a decent crouch-activated perk like Firmly Planted, which works well on sniper and fusion rifles and would mesh seamlessly with Head Rush, shows up on neither the sniper rifle nor the fusion rifle. Like, this trait actually might have been KINDA OKAY if they had just put ANY effort into allowing decent roll combos.