Terrigenesis

Exposure to the Terrigen Mists, or Terrigenesis (sometimes called T-Gen or Terrigenation) is a process allowing Inhumans to inhale the mists obtained from the use of the Terrigen crystals in order to activate their Inhuman genes and ascend as metahumans.

Origin
Inhuman geneticist Randac isolated the catalyst for his people about 25,000 years ago. He named the material Terrigen. Having taken the work of the Kree, Randac intended to use it to evolve his people into weapons able to fight back if the Kree returned, creating controversy and dividing his people by his work. Exposing himself to the mists, Randac became a god-like entity with mental abilities equaling those of the Eternals.

He created a program of voluntary Terrigenesis which was eventually cancelled due to half of the subjects demonstrating non-human mutations. This led to the creation and implementation of genetic testing before being allowed to undergo Terrigenesis.

Process
When at the correct temperature and exposure to water, Terrigen crystals react to produce Terrigen mists. These vapors are then pumped into a flux chamber during the Terrigenesis process to be inhaled by an Inhuman.

Rules and Customs
Even among the Inhumans, Terrigenesis is not a common process and not every Inhuman will go through the process. In the past, all Inhumans were allowed to be subjected to the mists, but this produced radical and monstrous mutations and severely damaged the Inhuman gene pool.

In order to stop this genetic damage, every Inhuman is now required to undergo a strict genetic screening before being allowed to go through the transformation. This strict rule has allowed the Inhuman to restore their genetic diversity after being in place for many millennia.

Cocooning
During the Terrigenation process, an Inhuman will often form a cocoon around themselves. These pods are often called Inhuman Terrigenesis cocoons, Terrigen cocoons, Cocoons of metamorphosis, or simply Cocoons.

Not all Inhumans or Nuhumans develop cocoons. Petras Petragon and Kamala Khan, an Inhuman and Nuhuman respectively, both did not form a cocoon when exposed to the Terrigen mists.

The length of time an individual remains in their cocoon depends on how much Inhuman genetic code a person might possess, and how dominant or recessive those genes may be. The quantity and purity of the Terrigen that triggers the transformation also plays a role in how long an individual remains in their cocoon. Terrigenesis can also be incomplete, triggering a cocoon but not resulting in a transformation. Sometimes, an individual can even die while in their cocoon.

Transformation
The process of Terrigenesis will produce a new gene in the Inhuman's genetic coding or trigger latent genes, granting him/her powers and/or a new appearance. The results of Terrigenesis are impossible to predict.

A belief of the Inhumans is that Terrigenesis reveals the true nature of the beings who undergo it.

It has also been theorized that Terrigenesis responds to the needs, fears, or desires of the Inhuman as an individual or the Inhumans as a nation.
 * During the Silent War, Professor Cartwright stated that the Terrigenesis acted to give the subject his/her most desired or feared thought, just as Cartwright was given superhuman strength since he desired to be like Captain America.
 * During the War of Kings, Karnak stated that the high number of aquatic mutations among the Inhumans was possibly an anticipation of Terrigen mists to provide for the needs of soldiers to be effective in zero-gravity environments in a predominately space-based conflict.
 * June Covington stated that Richard Schlickeisen's mutation, an invisibility to technology, was "a magnificent enhancement for the 21st century" due to global electronic surveillance. She postulated that the Terrigen is sentient and receptive to the environment and society.
 * It has often been stated that Inhumans are born to serve a specific person.

Heredity
There is a hereditary transmission of Terrigenated attributes. Inhumans are often born with characteristics from their parents but are also frequently born with a strictly human appearance.
 * Stallior and his family were stated to have all obtained their centaur-like bodies due to the "hereditary transfer of Terrigenated attributes from ten generations", hinting that there may be or sometimes is a moment when Terrigenesis gifts set themselves into the genetic make-up and are transmitted through reproduction.
 * Lockjaw transmitted his genetic gifts to his son, Puppy, although Puppy's teleportational abilities included time-travel.
 * The Bird-People are born with wings due to their selective breeding.
 * The Hidden Ones are gifted with the same persuasive abilities along with a similar appearance. Each Hidden One was also granted with individual powers and mutated visual appearances.
 * Ahura Boltagon has demonstrated sonic abilities much like his father. He has also demonstrated limited telepathic abilities and insanity, like his uncle.

Secondary Terrigenesis
Passing twice through the Terrigen mists, called Secondary Terrigenesis, is seemingly a dangerous procedure. It was first alleged that it was never performed by the Inhumans but was revealed as an uncommon occurrence.

Successive exposure to the Terrigen mists was stated to further the extent of already-existing mutations. When Gorgon was subjected to the mists for a second time, his animalistic mutation was developed further.

Inhumans
The Inhumans who undergo Terrigenesis demonstrate a nearly unlimited diversity of powers and mutations.

Shapeshifters
According to an alternate reality version of Reed Richards, Inhumans with two distinct forms are rare, making Devlor an Inhuman mutant.

Andrew Garner was gifted with abilities that resembled shapeshifting. Garner spent periods of time between his human form where he exhibited no Inhuman abilities and a monstrous persona known as "Lash" where he showed a complete physical transformation and had energy-based abilities. The reason for this transformation is due to him emerging from his Terrigenesis cocoon before he had fully-transitioned into his Inhuman form. Once his transition was complete, the Lash persona took over with no possible return to his human form.

Non-human mutations
The development of radically non-human mutations are seen as a bad Terrigenesis result. Under the reign of Randac, half of the subjects who underwent Terrigenesis were affected with such results. Under the reign of Gral, the whole population was forced to undergo Terrigenesis, and three-fourths of the population were transformed into non-humanoid types.

Hybrids
Terrigenesis is authorized for only pure Inhumans and is denied to any descendants of humans. However, there are a few cases of Inhuman hybrids undergoing Terrigenesis.

Deviants
It is unknown, and seemingly unlikely, that the known Deviant/Inhuman hybrids Maelstrom and Ransak underwent Terrigenesis.

Eternals (Deviant Mutants)
Following the detonation of the Terrigen Bomb, Thane's lineage was revealed, presumably along with the Deviant syndrome mutation of his father.

Humans
While the Genetic Council and the genetic screening prohibits Terrigenesis to any Inhuman with human lineage, there have been many instances of an Inhuman descended human undergoing Terrigenesis.

Using the Terrigen Bomb, a cloud of Terrigen mist was released by Black Bolt into Earth's atmosphere when Thanos invaded Attilan. This affected all humans with Inhuman ancestroy around the world, causing them to undergo Terrigenesis. These resulting superpowered individuals from this event became known as Nuhumans.

For more information on the Nuhumans, see here.

The mists released from the Terrigen Bomb do not seem to have any affect on baseline humans. Karnak stated that the bomb did not release Terrigen mists, since Hank McCoy confirmed that all data suggests that the mists are toxic to humans.

Professor Cartwright, who was exposed to the mists and developed a strong musculature, caused the United States President to order more experiments on humans. The Terrigenesis gave him what he most desired but condemned him to die soon after his transformation, his body quickly decaying. A dozen United States Marines willingly subjected themselves to Terrigenesis, after which they developed powerful mutations but also condemned themselves to dying as well. Prior to dying, these Terrigenically-enhanced humans experienced dizzy spells, nausea, and itchy scalps, resulting in death within days or weeks. The manner of death depended on the individual human: Cartwright's mutation resulted in enhanced musculature system and his body decayed while a Marine who developed psychic abilities suffered from a cranium implosion.

In rare cases, some humans who were exposed to Terrigen mists were able to develop powers without dying, though the powers they developed were unstable: In Earth-199999, humans with no Inhuman lineage are unaffected by pure Terrigen. Attempts to make artificial Terrigen crystals and mists, however, often have devastating effects on humans.
 * Brock Rumlow developed the ability to fire energy blasts from his face but later lost his power.
 * Aamir Khan was ostensibly exposed to the Terrigen mists and developed the ability to erect psychic force fields around himself.
 * Jiaying and the Inhuman community at Afterlife synthesized Terrigen crystals from the Diviners. These crystals were contaminated with the Diviner metal, which is lethal to humans. Anyone with no Inhuman lineage were petrified if they were exposed to the mists produced by these crystals.
 * Holden Radcliffe's attempts to replicate the Kree experiments that created the original Inhumans for Hive resulted in the creation of Alpha Primitives. These Primitives were gifted with enhanced physical abilities but were grotesquely tranformed and had diminished cognitive abilities.

Mutants
Luna Maximoff, the daughter of a mutant and an Inhuman, was tested by Reed Richards and stated that her mutant and Inhuman genes cancelled each other out, leaving her as a human. She was consequently denied Terrigenesis by the Genetic Council.

At age six, she was exposed to the Terrigen mists by her father and was granted Inhuman abilities but suffered both dependency and loss of control of her powers.

Quicksilver and Beast, both inspired by divine visions, asked Black Bolt and Medusa to use the Terrigen mists to reverse the effects on the mutants depowered on M-Day. Both requests were denied due to the necessity of a genetic screening and the rule forbidding humans or human descendants from undergoing Terrigenesis.

After receiving the Terrigen mists, several mutants were repowered, but at higher and uncontrollable levels: It was believed that for their powers to be fully restored, the mutants had to repeatedly expose themselves to the mists. Through repeated inhalations of the mists, Quicksilver absorbed the properties of the Terrigen mists, having his hands and chest encrusted with Terrigen crystals.
 * Quicksilver gained the ability to vibrate his atoms in order to perform limited time-travel and communicate with his future selves. While his power initially caused him to decay, he later learned to generate his own duplicates using these powers.
 * Callisto recovered her heightened senses beyond her former level, causing her to suffer from any sensation and consequently cause her to fall into a coma.
 * Wicked's spirits came back, but she was quickly overwhelmed by her parents' ghosts.
 * Freakshow was able to turn into his monstrous form but seemingly remained in that form.
 * Purge's superhuman strength was restored at a higher level, but he quickly lost control of his power as his muscle mass continued to grow.
 * Hub's teleportation was restored but her internal radar was quickly shut down.
 * Shola Inkose's telekinetic ability came back, along with his nightmares.
 * Hack's telepathic abilities were restored.
 * Unus's force field came back, but he lost control of it and blocked everything from him, including sound, air, and lights, suffocating him.

Eventually, the effects of the mists faded naturally.

Alpha Primitives
While exposing themselves to a high dose of Terrigen mist, three leaders of the Alpha Primitives riot transformed into an entity composed of three spheroid forms emitting an aura of mental energy, the Trikon.

Skrulls
The Skrulls have proven to be sensible to the mist. During the Secret Invasion, Medusa tortured a Skrull by throwing him into the mist repeatedly, developing random mutations along with great sufferance. Among the mutations were a furry gorilla-like arm, a seemingly autonomous snake-like being emerging from its body, and an additional face with glowing eyes developing on the side of its head.

Similar Processes
The Kree experiments and technology has allowed other processes, similar to Terrigenesis, to be achieved:
 * Amphogenesis
 * Antigenesis
 * Exogenesis
 * Isogenesis
 * Xerogenesis