Everything stated here is my opinion unless noted and/or cited otherwise. As a progamer for several years now, I have a wealth of personal experience and observations to draw upon. With that said, I sometimes have to speculate due to lack of studies/concrete facts.

Overview:

The disruptor is Protoss's new area of effect damage dealer in Legacy of the Void. It requires a robotics bay to build and comes from the robotics facility. Due to the colossus's nerfs in LoTV (-1 range & 20% damage reduction), many protoss use the disruptor to replace the colossus. The disruptor requires significantly more control and management than the colossus of old and is only really effective when paired with a warp prism. If your opponent is paying attention they can mitigate most of the blast, but even if the disruptor misses you can still save it with the extended pick up range of the warp prism. Without a warp prism's support, a disruptor will almost always die after exploding due to its low movement speed and hitpoints. In addition, the disruptor is much less effective against faster units due to their increased ability to split as well as larger units compared to the colossus because it will tend to hit fewer of them at a time. In terms of positioning and utility, the disruptor is more similar to psionic storm in that you want to come from the sides and back while pressing the front to force your opponent into taking a lot of damage from the blast. Flanking with the disruptor is pretty difficult, but critical to using it effectively.

By the numbers:

Cost: 150/300
Health: 100/100
Armor: 1 armor
Movement speed: same as a marine, slightly faster than a stimmed marine while purification nova is active.
Purification Nova: Gain 67% increased movement speed, invulnerability and lose all unit collision for 3 seconds. Then deal 145 damage in a small AoE around the unit. Splash is ~1 radius. ~21 second cooldown. Note that the disruptor deals friendly damage.

Terran vs Protoss

As things are right now, the disruptor sees limited use in this matchup. Until protoss is able to get a substantial amount of blink stalkers to accompany the disruptors, terran will usually have the option to lift everything up and boost away if they are unable to split in time. Stimmed bio has little issue splitting against a disruptor given enough warning time, but demands that the Terran remain on edge. The primary danger to Terran is when the disruptor comes from an unexpected angle as your reaction time will be reduced as well as the area in which you can flee. If a disruptor comes from the back, you may have to run to the side while in range of your opponent’s army leaving you vulnerable to forcefields and potshots.

Mana uses the disruptor to harass my army.




By bringing the disruptor in from the back Mana makes it much harder for my army to effectively split by reducing reaction time and safe area in which to retreat to.




Protoss vs Protoss

There are 2 main problems with gauging the disruptor's usefulness in PvP. The first is that few protoss actively play LoTV ladder and weekly tournaments besides Take's LOTUS Cup. So there haven't been as many games to see how the meta is developing. The second is that adepts dominate the early game of this matchup and can end the game very quickly. As players get better at surviving the early onslaught of adepts, the mid and late game will be seen much more often, but right now games tend to be on the shorter side. In the most recent LoTV patch preview, disruptors will be receiving bonus damage to shields making them more effective in this matchup. With the bonus damage disruptors may be the answer to the mass Adept style that is so common right now. Disruptors have a lot of potential vs adepts because adepts are relatively small and thus clump. Add to that the fact that adepts move relatively slowly, and there's a lot of potential for disruptors to counter them effectively.

Mana uses the disruptor to harass Nightend's mineral line.





Mana drops a disruptor on the high ground forcing Nightend to split his army. While the prism dies, the disruptor is able to escape due to good forcefields.



Mana uses the disruptor to force Nightend to split his army up and reduce his overall DPS in this fight.





Mana's Disruptor does little to Nightend's army. Due to the obvious approach and lack of a fight, Nightend is able to split and take almost nothing. Despite that, the warp prism allows the disruptor to escape.




As the fights get bigger and there are more things to do, it becomes harder to react to the disruptor in time.




Mana's disruptor comes directly through Nightend's retreat path leaving little space to escape the blast.



Protoss vs Zerg

While the colossus cleaned up zerglings with little trouble, the disruptor does not deal with zerglings effectively due to fear of friendly fire and the speedlings high movement speed. That doesn’t matter as much, though, because the adept has basically outlawed heavy speedling compositions in this matchup. Adepts are so incredibly strong vs speedlings that most compositions from zerg will center around roach/hydra/lurker or mutalisks. As the disruptor’s explosion doesn’t hit air, mutalisk based compositions with a relatively quick tech to vipers as needed can greatly reduce the disruptor’s usefulness. If you opt for a ground based army, then creep spread will be incredibly important to mitigating the disruptor’s explosions. Off creep, hydras, in particular, will have a tough time splitting against disruptors.


Nightend efficiently uses 2 disruptors to clean up some roaches from a nydus.




Nightend stacks 2 disruptors in order to oneshot Neuro's lurkers.




Nightend deploys disruptors mid battle forcing Neuro to run and split his units.




Off creep, Neuro has a lot of trouble splitting his units enough to avoid taking damage even though there's no battle currently going on.



In summary

The disruptor is a powerful area of effect damage dealer but requires a lot more babysitting and micro management than any other unit in the Protoss arsenal. It's a big investment in both tech, resources and its demand for support units, as a warp prism is almost required to keep it alive. Initially, players may find the disruptor to be relatively useless due to its high skill requirement, but the disruptor has the potential to completely swing fights when used effectively.


Thanks to Nightend for providing replays and Protoss insight about the disruptor and its utility, and to Bly for helping me understand the situation better from Zerg's perspective.

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Previous installments:
Liberator in Review
On SC2's Social Features
Re-thinking the Ladder