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.
While this perk does do an alright chunk of extra damage per rocket, I wouldn't exactly call it a huge DPS trait. The bomblets from each Cluster Bomb generally spread a decent bit away from the central explosion; they sometimes vary in exact spread and detonation height, they mostly affect the area around the rocket's impact rather than said direct impact. Against the absolute largest targets, you might hit up to 4 or 5 bomblets, but against average-sized bosses, you might hit up to 3 at the very most, often less. This is better than nothing, but generally inferior in the single-target DPS department to options like Clown Cartridge, Lasting Impression, Chill Clip, Explosive Light, or Frenzy. I'd only take this perk for this purpose if the Rocket Launcher in question can get it column 3 (like BrayTech Osprey) or if it's an old one that barely has any other options (like Hoosegow).
However, what Cluster Bombs excels at is add-clearing. Believe it or not, Rocket Launchers *can* be used to clear adds as long as you have a build that allows you occasionally throw a rocket into a big clump of enemies to quickly clear them out; or to punch a stunned Champion in the face with one, and let the blast radius take out any nearby adds. Cluster Bombs makes Rocket Launchers much better at this by expanding their effective Blast Radius, either complimenting 'Launchers with a high Blast Radius or compensating for one with a low 'Raidus.