"There was no long-term, and trying to cling to one would only spoil it all."
This article contains spoilers regarding the ending of Worm and plot of the sequel.
Broken triggers or the structural issue are a type of extremely violent trigger event first observed after Zion's death, in which shards appear to disobey their intended behavior, often leading to the deaths of their hosts, as well as bystanders.
The visions from broken triggers are often disjointed and come in waves. Some will replay the last memories of Zion, while others are so quick that no one sees anything. When near a broken trigger, Rachel Lindt appeared to see Zion's memories of the mockeries of Eden, or of killing Eidolon. At another broken trigger incident, Victoria Dallon saw similar visions of either these mockeries or Eden herself. Unlike typical trigger visions, those who saw visions from broken triggers were able to remember what they saw.
At least one victim of a broken trigger seemed to have gained awareness of the nature of shards, sensing the presence of the shard and expressing concerns about being incorporated into the shard's memory.
Broken triggers appear to display an almost shaker effect, allowing the shard to jump from person to person, affecting multiple people. This was possibly due to the now-unrestricted shards registering people as a triggeree, where before they would only connect to more then one person if that person was also having a trigger event. The position within the 'area of effect' of a broken trigger seems to affect its manifestation; in one incident, those farther from the center of the trigger event were less mobile, to the point that those on the perimeter were fixed in place by their shards.
Whereas typical parahumans were protected from the effects of their own powers, via the Manton Effect, those affected by broken triggers almost invariably died as a result of their powers or the trigger event. One incident involving a broken trigger fixed a victim's Corona Pollentia in place, leaving her unable to move without intense pain until her death; multiple others also died from the same condition. The same incident, centered around a matter manipulation power, also generated capes whose powers killed themselves; one vomited a fractal-like tree which tore away his body, while others were buried by their powers.
When a parahuman undergoes a broken second trigger event, they merge with their shard and become a Titan. As part of this process, the shard becomes the primary conscious actor of the resultant titan, acting according to its goals. The requisite loss of personality varies depending on the parahumans psychological state. Those that were able to scrounge some consciousness during the trigger and decided to seize the power, stay in control to some degree, or at least art able to influence their Shards decision making in a manner similar to how shards can influence the host normally. Those, that choose to surrender to the power, appear to experience a loss in their original personality, attacking seemingly indescriminately.
Without a hub for the shard network (namely, Scion, the primary intelligence/consciousness of the entity), individual shards could no longer get permissions to alter themselves or their behaviours, or coordinate with the greater network in this task.
Case 53s and lethal vial triggers can be considered more benign variation of broken triggers. However, Eden had no time to configure host-shard connection before her demise, and the most of Cauldron vials were consumed before Eden's body was fully destroyed, so it is not completely clear if 'undercooked' process or 'lobotomized', but somewhat intact hub, had bigger influence in those cases being (not) as bad as they were.
So far Broken Triggers can be traced to Zion-derived, natural occurring connections, which unable to proceed properly without his guidance.
While odd triggers and strange powers were a fact of life for parahumans, they were generally following an internal logic. With the death of Scion, the shard network lost ability to maintain itself.
A broken trigger occurred in the nascent city, getting in the way of a domestic dispute that Bitch was resolving; it consisted of a parahuman who spread black ooze with each injury, gradually damaging himself before he died and spread it to a second host.Miss Militia stated that it was the fourth such trigger known, possibly twenty percent of the triggers since Gold Morning.
Broken triggers had become a common part of life in The City. One of the worst such incidents occurred as a riot brewed among local construction workers, until another broken trigger ensued. Despite the efforts of the heroes on the scene to help those affected, numerous people intentionally entered the affected area to try and get powers, while those who were affected were killed by powers or the triggers themselves; ultimately, ninety-two people died as a result of the incident.
Six of the victims of the riot incident were citizens of Earth Cheit, straining the relationship between Earth Cheit and Earth Gimel and causing the former to threaten war on the latter.
The 'Black Ooze': created black ooze that morphed into tentacles and fronds, generating more upon being damaged. Once the first host was killed, the trigger seemed to spread to another host. 
Casey Forks: generated mold, which he could use to puppet bodies and make machines work. Like other broken triggers, he is implied to have died.
Incident at the construction worker riot: a blaster trigger that spread exponentially throughout those nearby, with powers themed around matter creation or manipulation, folding matter into various origami-like shapes to cause various effects.
A dog who triggered with the power to generate a field of slowed time, accidentally trapping and killing people before being put down by Valkyrie.
The Mayor of Killington: Broken triggered into enormous worms.
↑There are no copies of the same power, barring a circumstance where it’s powers recurring within a second/third generation cape. Even then, debatable. - Comment by Wildbow on Interlude 20.y
↑Faces. Mockeries. Variations on a theme. Reaching hands, supplicating.
-The image was brief, but acutely familiar. Rachel felt mentally disoriented in the same way she might be physically disoriented if she stepped forward and found the ground wasn’t there. Others in the area had staggered. Miss Militia had dropped the hose for the foam gun.
The cape who’d shot him hurried to run-
A moment of uncertainty. The population of this world wasn’t reacting any further. He attacked, they moved. Again and again, they created the images. They weren’t afraid, and he was.
-but stumbled as the mental image shook him. He managed to get his footing, but the ooze moved faster with each passing second, and the delay had cost him. It slopped around his ankles on its way past him. - Excerpts from Teneral e.4
↑ 3.03.1The visions, they’d been broken up, too recent. She wasn’t forgetting them. The power, too… he’d been strong.
A man in a white hood and cape stood there, the tension in his body swiftly stopping. He had no expression, only a green and blue glow beneath his hood, but his body language was clear. Shock, defeat.
A flash of golden light wiped him out of existence.
↑The fragment of a trigger vision hit me. The latest wave.
I saw only a flash of faces, and in seeing those faces, I saw the phantom self that clung to me. The impression lingered for only a moment before I realized the faces didn’t resemble mine. - Excerpt from Flare 2.4
↑“I can feel it,” the man said. He wasn’t paying much attention to Rocketround. “All the way down to this vast well, partially filled with potential energy. Like I’m on the lip of a volcano and it’s an impossibly long fall with only magma at the bottom. I don’t know if I’m better off throwing myself down into that or leaving it alone.”
“Leave it alone,” I said, my voice joining more than one other person’s.
“What if my thoughts and brain get made into a part of that? One piece in that thing’s construction. What if it makes me immortal, forever a part of this thing? A recording of me in there, how I think, how I do things.”
“We’ve studied parahumans, powers and power sources a lot,” Roadblock said. “We’re pretty sure that’s not a thing.”
“Yeah,” the guy in the clearing’s center said. “But…”
He trailed off.
“It’s not a thing,” Rocketround’s voice joined Roadblock’s.
“But I’m standing closer to it than you are,” the man said. “And from where I stand, I feel like it might be.” - Excerpt from Flare 2.4
↑ 6.06.1“They tend to cover a lot of ground. Shaker stuff.”
“Yeah,” Rocketround said. “That’s come up in briefings.”
“Location, environment, and position matters a lot,” I said. “The capes closest to the perimeter were least mobile. I think the further they got from the center, the less flex there was. Until their agents wouldn’t let them move at all.” - Excerpt from Flare 2.4
↑Stephen M (Ethesis): I keep thinking that nine clones tapped into one passenger should each get just 1/9 of the power each.
Wildbow: Nope. See the Echidna clones for a similar situation where powers aren’t divided. - conversation on Interlude 25
Peanuckle: What I'd like to know is what sorts of abilities the shards can perform without limiters. Judging by QA and Khepri, shards are pretty much bullshit. But what about shards like Grue's, or Tattletale's, or Grey Boy's, acting outside a host to defend their Entity-body? Is there any comparison, or are "unshackled" powers so far beyond what we see that it's laughable?
Wildbow: Look at Noelle or the Bitch epilogue chapter for what a shard does when it's really unleashed - depending on the host, the nature of the unleashed power can vary, specializing as it develops toward a task/specific implementation.
Grue's power would just spew darkness out in very direction to pretty much blanket and isolate an entire city, his body would become a vehicle for the power, and he'd mutate, quite possibly turning the 'tap into other passengers' ability into a link to just absorb power. Broken/dead shard, he'd continue doing so until those passengers lashed out, creating isolated, power-based effects/chunks of Grue in the midst of the city.
Tattletale's power would just scale up constantly in power, reach, and intensity of detail. The shard might not have broken 100% clean - Scion might have given it some tools somewhere in there, so I can imagine a Tattletale-sub-entity scaling up to a breaker state or tapping into a tinker ability to network/develop more hardware/brainware to process it all. Scale up to processing multiple dimensions at once, and develop/manifest/obtain a weapon. Going back to the tools Scion gave, a simple blaster power with a clean, possibly invisble terrain-penetrating laser, with Full-bore-tattletale focus at work to discern the best possible weak point? Or even just a Tattletale in the middle of it, holding a gun? Picture her systematically picking off threats one after another, from highest priority to lowest, from the center of the incident sites, maximum range.
Basically, you unshackle, the power scales up, the mind/body start to break down, and if the host is lucky, the shard can provide some means of housing the new data and form.
Standalone, without a host, the manifestation for the shard itself confronted in its own world, would be very similar in execution. - Comment byWildbow in Spacebattles
↑Her brain. The Corona Pollentia, the means by which powers were operated by the parahuman. Hers had been established, but not as a fluid, functional thing. It was a nail, taking her brain and fixing it to a specific position in reality. - Excerpt from Flare 2.4
↑I saw eyes widen, and turned to look. A man had opened his mouth, and had something that looked almost as tall and thick as a telephone pole spearing skyward from his mouth. Blood streamed from the sides of his mouth, his jaw clearly dislocated, and more fluids painted the length of the pole as it continued to rise. It reached its maximum height, and then forked, the upper half splitting out into two equally thick portions, a giant ‘Y’ shape. Each branch then forked into two, and forked into two again.
I flew to the man who’d grown the tree. Even before I reached his side, I could see the damage that had been done. Jaw, throat, chest, and stomach had been torn away. Traces of the same material that had formed the tree had collected in his insides and pelvis, breaking into jagged pieces at some point before or during the tree’s fall. - Excerpt from Flare 2.4
↑There was small talk, people remarking on what they’d seen. Horrible things. People buried alive by their own powers. A few cases like what I’d observed. - Excerpt from Flare 2.4
↑She could feel that well of power. [...] She made the decision. She reached out and seized it. - Excerpt from Flare 2.4
↑What is ‘death’? Death is stasis. Death is disconnection. Disconnection from all communication, disconnection from other wells of power. I have what I have. I cannot grow. I cannot connect to others and seek their input or resources. - Excerpt from Heavens 12.all
↑it is what the humans call a second trigger. It is what humans call a broken trigger, though this is wrong.
It is a failure to support. A desperate clutching at a well too intense and dangerous, collecting waste and fragments, extrapolating out wildly, without program or logic. - Excerpt from Heavens 12.all
↑“This landscape added up once upon a time,” she said. “Everything interconnected, it fed more easily. Now it’s… a hundred hard drives crammed into one computer’s housing. Each agent lays some claim to real estate, builds their houses. But when information isn’t flowing freely, and some houses get built on broken or missing ground…”
“Broken triggers,” I said.
“And Titans, when there’s enough support from the system to keep them propped up." - Excerpt from Infrared 19.7
↑“Armstrong asked me to join a discussion about case fifty-threes, do some tests, get scanned, have some Thinkers look at us,” Sveta said. “Kenzie got some scans of things, others have their own data. We’re thinking maybe the case fifty-threes are closer to what Titans are than humans. Maybe there are insights there. It’s a bit of a reach, in my opinion.” - Excerpt from Radiation 18.9
↑She could see the capes fighting, down below. A man was at the center of it. He’d swelled in size until he was twice the height he should be, almost breaking apart, like a statue that had been dropped, only the biggest chunks preserved, hanging in mid-air in a vague human shape, high above the street. Black ooze gushed from foot-wide cracks and divides in his body. His flesh was dark brown, the edges of the cracks raw and bloody.
Even from her vantage point on the rooftop, she could hear his screams. It was muffled, despite the volume, as though he were screaming while underwater, the effect amplified. - Excerpt from Teneral e.4
↑“Shit happens,” Rachel said. “World makes a lot more sense when you accept that.”
"This is a little different from the everyday sh-tuff,” the man said.
Miss Militia nodded, her eyebrows knit together in concern. “This makes four. Almost a fifth of the regular triggers we’ve heard of. Two in three days. One’s still loose, the others died or destroyed themselves.” - Excerpt from Teneral e.4
↑Silence isn’t an option. Things are heating up, people are scared and we’re scared for a justifiable reason. Powers came out, and we started seeing broken powers. People with mutations, people with no off switch. Monsters who needed to be quarantined. Endbringers.
Now we’ve got a different kind of broken power.
It keeps getting worse. It gets worse in a linear and steady way. These things follow from one another. There is a visible pattern and there is a sense to be made of things. The new broken powers follow from the people made monstrous by their powers. If Weld knows something we have to ask. [...] every week we get a handful of reports of people triggering with broken powers. They burn bright and burn fast and they do a lot of damage.
on the smallest level we are quiet and still because we are afraid to disturb the peace. but on the big level our new neighbors aren’t focused 100% on us. we’re important. we’re a powerful few even though we lost 1000000000s. the tyrant queen is looking at us but also watching over her shoulder for the war world and the monsters and the broken triggers. the war world is wanting to venture out but maybe an expedition is hard to field and they get broken triggers too. they’re getting more regular triggers. - Excerpt from Glow-worm P.8
↑ It had been ten days, now. Ten days after the broken trigger with the citizen workers. One of the worst we’d seen for citizen casualties and damage. - Excerpt from Flare 2.4
↑“This beast is the cause of your mysterious deaths and incidents. It couldn’t know what it was doing.”
“I would guess it trapped prey by accident, and driven to the edge by hunger, it ate pieces of the accidental victims.” [...] “A dog with powers. I tried to feel around it, see why or how. I looked at the moment of the trigger. The poor beast had a refrain of human words running through its head at a critical time, and the agent was damaged enough to try meshing with the animal, sick and diseased as it was.” - Excerpt from Interlude 9 II