First off, I believe this set is just the latest symptom in a long line of misguided attempts to fix game mechanics by releasing new sets - but that's how ZOS likes to do things for now, so I won't get into it.
- (2 items) Adds 1487 Offensive Penetration
- (3 items) Adds 129 Weapon Damage and Spell Damage
- (4 items) Adds 129 Weapon Damage and Spell Damage
- (5 items) Dealing direct damage to an enemy, who is not a Plague Carrier, turns them into a Plague Carrier for 10 seconds, dealing 1715 Disease Damage over the duration. If the plague is removed early, it explodes, infecting enemies within 8 meters of the carrier and dealing 712 Disease Damage. The explosion deals an additional 50% damage per enemy hit. This effect can occur once per attack and scales off the higher of your Weapon or Spell Damage.
It was designed to "punish larger groups for casting Purge with reckless abandon" - And it did that in a way; such that you're either part of a "Ball Group" which has the defenses/healing to power through it any way, or you're a part of disorganized rabble which will get absolutely obliterated if someone decides to use a Cleanse Synergy.
Anyhow, I digress. The set does make it punishing to spam Purges - but it does so much more than that. I use it in Cyrodiil, sure. But I also use it in Battlegrounds, or in PVE (yes, the dot/explosion also applies to PVE monsters) - things don't even have to be Purged, if a target dies they explode just the same (the tooltip fails to mention that, but it's there. Case in point; it works in AOE farming PVE)
At this point it's simply better than most other damage sets for Stamina (potentially).
Compare it to a set like Syvarra's Scales
- (2 items) Adds 1206 Maximum Health
- (3 items) Adds 1096 Maximum Stamina
- (4 items) Adds 1096 Maximum Magicka, Reduces your damage taken from Guards by 20%.
- (5 items) When you deal damage, you cause a burst of lamia poison that deals 900 Poison Damage in a 5 meter radius and an additional 10272 Poison Damage over 6 seconds to all enemies hit. This effect can occur once every 7 seconds and scales off the higher of your Weapon or Spell Damage.
Viper's Sting
- (2 items) Adds 657 Critical Chance
- (3 items) Adds 1096 Maximum Stamina
- (4 items) Adds 657 Critical Chance
- (5 items) When you deal damage with a Martial melee attack, you deal an additional 6400 Poison Damage over 4 seconds. This effect can occur once every 4 seconds and scales off the higher of your Weapon or Spell Damage.
or Sheer Venom, which can only be applied with Execute abilities.
- (2 items) Adds 1096 Max Stamina
- (3 items) Adds 129 Weapon and Spell Damage
- (4 items) Adds 129 Weapon and Spell Damage
- (5 items) When you deal damage with an Execute ability you infect the enemy, dealing 6576 Poison Damage over 6 seconds and dealing up to 100% more damage to enemies under 100% Health. This effect can occur every 6 seconds per target.
These sets do 1712, 1600, or 1096-2192 (at best!) DPS with their procs. Plague only does 1177 - lower, but somehow still comparable no?
Disregarding for the moment how Plaguebreak has an almost ideal offensive stat line of Penetration, Weapon Damage, Weapon Damage, you might prefer one of above sets in a 1v1 scenario - assuming your opponent doesn't use any sort of Purges - but in virtually any other scenario, Plaguebreak far outshines these sets (and most other proc sets at the moment)
Say you're a Warden - who, like most Wardens, likes to use Betty Netch summon, which purges a negative effect once every 5 seconds. If you're fighting, say, a stamDK with Plaguebreak, you'll probably be hit with Noxious Breath (Dot+Major Breach), Venomous Claw (DoT) and the Plaguebreak. Leaving you with a nice 25% chance to nuke yourself (and anyone around) if the Netch happens to purge the wrong effect.
Or say you're a Templar, and you like to use Cleansing Ritual (either morph) because it's a nice aura for dueling in (healing/damage) - better hope no one has Plaguebreak on you, because that's gonna hurt - incidentally, any rando who uses your Synergy might also nuke you.
Now, you might be thinking;
well, Vicious Death can also be used to nuke groups like that. But I would argue that Plaguebreak is simply stronger than VD in every way.
Now, for a reference Weapon Damage of 5500 (not at all optimal, but just a reference point), Vicious Death does 18500 death-explosion damage.
Plaguebreak "only" does 4000, but it scales with 50% per target. Meaning that Plaguebreak would out-damage VD once there are 4+ enemies hit. Considering that Plaguebreak also has greater radius (8m vs. the 5m of VD) this is a fairly easy condition to meet, even in Battlegrounds.
Furthermore, while VD's (5)-piece bonus is USELESS in 1v1 scenarios, Plaguebreak remains very competitive with other DoT-proc sets. And in all this, we're not even taking into account that Plaguebreak reacts to purges.
I'm not sure exactly how this set should be nerfed; but I definitely think it should be - and I'll find something else to use, but right now it's simply too good to pass up.
I think ZOS should instead look towards "fixing" these game mechanics by... actually changing the game mechanics, rather than this patchwork of item sets.
Make a Purge cost-buffer like what's existed for roll-dodges and Streak/Ball-Lightning for years, so you can't spam it senselessly? Reduce the efficiency of things like purge, such that players at least have to build towards purging, if they want to keep it up?
I don't have all the answers, of course, but I'm fairly certain Plaguebreak isn't it.
ZOS's own descriptions of the set, for refererence:
"Similar to Dark Convergence, we targeted large groups again with this set, focusing on their ability to have numerous purges running, making locking them down and bleeding them out incredibly difficult to do. Now, larger groups must purge more carefully, running the risk of setting off ticking time bombs and having to heal up the aftermath instead of repeatedly casting it with reckless abandon"
https://forums.elderscrollsonline.com/en/discussion/584299/pc-mac-patch-notes-v7-1-5-waking-flame-update-31
Currently, this set feels like it is a better version of most Damage over Time sets, such as Hunter's Venom or Viper's Sting, where it can output decent pressure but with the added bonus of an explosion if removed early. We've toned down both the Damage over Time and the damage of the explosion against low target counts, while increasing the damage against large target counts to ensure it continues smashing groups who are chain casting purges with reckless abandon. Overall, this should help reduce the need to purge the set and make it far less oppressive to fight against as a solo or low group count player.
https://forums.elderscrollsonline.com/en/discussion/590109/pc-mac-patch-notes-v7-2-5-deadlands-update-32
EDIT:
For those commenting on it being a "Stamina set" - If you use it on weapons/Jewelry there is absolutely nothing about it that makes it maladapted for magicka builds - in fact, I've seen plenty of magicka builds using this.
It's Offensive Penetration, Weapon/Spell Damage, Weapon/Spell Damage and a proc which scales of the higher of your weapon/spell damage - perfectly fine for any build, as long as you don't use it on body pieces.
I think it is central to ESO's well-being to critique the developers when they change the game (or fail to change something).
But the negativity can be exhausting, so I vow to post 50/50 negativity and appreciation.