Trigger

Trigger (トリガー) is a type of drug that gives a boost to an individual's Quirk, simultaneously weakening their sense of reason.

Overview
Originally, Trigger was created to massively enhance the power and potency of weak Quirks. However it was soon used for criminal activities, so it was banned in many countries, including Japan, becoming an illegal product with which gangsters and drug dealers around the world traffic.

Trigger is produced in different regions of the world, so its quality can vary from one place to another. Those produced in Asia are usually of poor quality and their effects only last a few minutes, while the Trigger produced in America can last an hour or two.

Trigger addicts suffer a side-effect after the use that changes their tongues' color to black.

Generally, Trigger is injected into the body, but it has been possible to develop a variant that only needs to be ingested to work. Although it's less effective than the other form, it lacks the psychotropic element.

My Hero Academia: Vigilantes
In Japan, criminal mastermind All For One, as part of an organization known as the Villain Factory by the police force, shows a special interest in the effects caused by Trigger, having helped to create a new variation of the drug known as Ideo Trigger. This version causes its consumers to turn into Instant Villains and go on a rampage. He first utilizes this form of Trigger secretly behind the scenes of the Underground Masquerade, enticing fighters with a concentrated dose of the drug to help them perform better in fights, and then using the Ideo Trigger to gas the Masquerade, exposing and causing the fighter's Quirks to go out of control, and allowing him to steal the ones that most interest him.

Several years later, the Villain Factory returns, deploying several agents onto the streets of Naruhata, distributing the drug between junkies and thugs, which causes many problems, allowing them to collect all the data to study, as well as blood samples from the consumers. Any Trigger users that most interest them are abducted and turned into Next-Level Villains, altering and enhancing their bodies to make them able to withstand massive amounts of Trigger. This leaves them drastically and indefinitely altered from the dosages.

My Hero Academia
In order to obtain funds for their experiments, the Shie Hassaikai is engaged in trafficking with this drug with other criminal organizations.

Months later, a factory that illegally produced this drug was destroyed, although the manufactured product had disappeared. A few days later, a trio of smugglers try to transport the drugs by sea to deliver it to their client, Flect Turn, but are intercepted by the Oki Mariner Crew, so one of them injects a dose of Trigger to power up his Quirk and generate a dense smokescreen to escape and hide in the Verize islands.

Due to the danger posed by the Trigger and the fact that it is difficult to search for someone in the archipelago, Selkie enlists Ryukyu and her team for help. Together they go in search of the smugglers and this time they manage to catch them and confiscate the large drug shipments.

Unbeknownst to them at the time, the smugglers were working for the international cult, Humarise, and had already acquired enough Ideo Trigger for their plans. With the help of several scientists which they forced into assisting, Humarise created Trigger Bombs, which contain a massive amount of Ideo Trigger gas, that when unleashed, cause whoever to consume its Quirks to go completely out of control to the point of overload and death. They plan to use the gas to infect major cities all over the world, killing most of the Quirk population, thus preventing the Quirk Singularity and saving humanity.

Pro Heroes are deployed all around the world to stop Humarise and Trigger's threat, and thanks to a deactivation key created by one of the scientists, Eddie Soul, Izuku Midoriya and the scientist's son, Rody Soul, manage to shut down the master Trigger Bomb, halting the activation, while the Pro Heroes find and dispose of the Bombs themselves.

My Hero Academia

 * A minor villain amplifies his blades, sprouting a great number of very long blades from his body. He is capable of controlling them, sprouting and retracting them, as well as focusing them into one place to reach great destructive power. They become sharp enough to nick Eijiro Kirishima's Hardening.
 * Joi Irinaka of the Shie Hassaikai amplifies his Mimicry, allowing him to affect much larger than the physical area of a refrigerator, his normal limit, and to merge with and manipulate an entire underground facility in preparation for the heroes' invasion.
 * Rikiya Katsukame of the Shie Hassaikai amplifies his Vitality Stealing, allowing him to use it without making physical contact with others, absorbing stamina by simply inhaling.
 * A smuggler injects himself a dose to boost his Smoke Quirk and create a large smokescreen so his gang can escape. Another also tries to inject Trigger but is stopped by Selkie before he gets a chance.
 * Ending amplifies his Whiteline, allowing him to control any lane lines painted on the road.
 * An entire city is effected by the Ideo Trigger gas, which results in the entirety of its Quirk population to overload of out control before each of the user's end up dying.
 * The Serpenters amplify their Quirks, transforming their face to become more monster-like, and sprouting blades from all over their body.
 * Leviathan dosed up on Trigger fights completely blindly with no real sense of self.

My Hero Academia: Vigilantes

 * Rapt Tokage amplifies his lizard appearance to a strong Pterodon Physiology Quirk.
 * Moyuru Tochi, who only appeared to have a small flame in place of his hair, is amplified to become a powerful flaming rock golem.
 * Soga Kugisaki amplifies his Spike to a Porcupine Physiology Quirk, that sprouts stronger spikes all over his body.
 * Mario Kugutsu is transformed into a massive four-armed giant.
 * Akira Iwako, whose Quirk was amplified to a Hardening transformation-type Quirk, with additional Enlargement and Super Strength abilities.
 * Teruo Unagisawa, whose Quirk made him somewhat resemble an eel, was amplified to an Electric Eel Physiology Quirk with a large eel's body and small human limbs. He also had greatly enhanced mobility, being able to bounce off the walls of buildings to launch himself into the air and even keep up with Pop Step's Leap. Teruo was later abducted by Kuin and seemingly injected with several doses of Trigger over an extended period of time, which lastingly modifies his body into a large electric eel with slippery skin, but this time with very muscular human limbs. He is able to discharge electricity, but doing so renders him unconscious. It is unknown whether this modification is permanent.
 * Kuin Hachisuka, while not initially a user herself, utilizes her Queen Bee Quirk as a specialized delivery system to infect dozens of Quirk-using citizens in order to effectively test drive Trigger's potency while in use. Later she uses it to transform her body, strengthening her and allowing her to use an electric quirk.
 * Ichiro Hotta, a Trigger dealer, had his Quirk amplified to become a humanoid grasshopper.
 * A civilian from Chapter 5 was amplified to gain blades on his fingers and shoulders, as well as Muscle Enhancement and Enlargement.
 * A civilian from Chapter 5 was amplified to release electricity from her eyes.
 * A civilian from Chapter 5 was amplified to release black fluid from his palms.
 * A civilian from Chapter 5 was amplified to catch on fire.
 * A civilian from Chapter 5 was amplified to become very large and round, with dark skin and lighter markings. His body also released streams of water from several points.
 * The fighters of the Underground Masquerade are infected by the Trigger gas, which causes their Quirks to go out of control.
 * Bee☆Pop is infected by Trigger, forcing all the Bees within her body to try and disperse.