Arcane Genetic Modifications

Arcane Genetic Modifications (AGMs) are a form of magical surgery providing arcane enhancements to Imperial citizens. Knowledge of magical biology is far more advanced in the Empire than in the west, and so in the Celestial territories such surgeries are far more common and accessible than elsewhere. Some ARGs remain experimental, but most are well-tested, and the Empire always seeks volunteers for experimentation. The most drastic AGMs, such as the GENASI procedure, can even change the creature's race and caste. Such procedures are highly restricted.
Those who create and perform AGM procedures are known as Arcane Geneticists, or, colloquially, 'Permuters.' They are expected to be of the Lotus Caste. It is illegal to be a Permuter outside of the Lotus caste, but in practice black-market AGMs are relatively common, although they tend to be of variable success.
Some AGMs are common, and can be performed over the course of an hour, or even instantaneously by drinking or injecting a solution. Some are extremely complex and rare, and take a surgery with weeks or months of recovery time. Almost all AGMs are permanent and cannot be removed without extremely complex magical procedures.
Many AGMS have special racial or class requirements. This is usually because certain procedures don't work on all races due to genetic reasons, or because they require certain abilities to function usefully. It is illegal for those of the stone or steel caste to receive AGMs without requesting permission from local officials. (How far these rules are followed, however, is less clear.) It was once entirely illegal for any aasimar to gain an AGM, as they are made in the Empress' image--and the Empess is perfect--but rules relaxed a decade ago, and they have now become very popular.

List of AGMs

This section provides Meta information for the mechanical effects of certain AGMs.

Choral Voice

Rarity: Uncommon
Race Requirements: None.
Stat Requirements: None.
Legality: Legal.
Procedure. Injection of elixir into the voice box, plus several days of vocal recovery.
Possible Complications. Extremely rarely, the procedure may backfire and cause muteness.
This procedure is popular with courtesans and other performers. It causes the adopter to speak with up to five tones at once (depending on the complexity of the procedure), creating an effect as if multiple voices are speaking simultaneously. This means that when the adopter sings, they can create a harmony--or a terrible cacophony.
After you adopt this AGM, you become mute for 1d4-1 days. Afterwards, you have advantage on Charisma (Performance) checks made to sing. Once per long rest, you may cast either Dissonant Whispers or Shatter (centred on yourself) at second level. Charisma is your spellcasting ability for these spells.

Endowment of the Kalashtar

Rarity: Very rare
Race Requirements: Human, aasimar, any elf or half-elf.
Stat Requirements: Intelligence, Wisdom or Charisma 18.
Legality: Offered by the government to selected candidates in the Lotus Caste. Otherwise illegal.
Procedure: Magical ritual preceded by brain surgery. Usually requires several weeks' recovery time.
Possible Complications: Procedure causes catatonia for about 20% of adopters, and less successful procedures may cause hallucinations and personality changes.
Those of the Lotus Caste who distinguish themselves as great arcanists, researchers, or priests are offered the chance to become Kalashtar, attuning themselves to the Veil itself. The procedure grants a number of psychic benefits and changes the creature's appearance, but it has a high incidence of failure.
This AGM changes your race to a Kalashtar, and changes your caste to Lotus.

Endowment of the Shadar-Kai

Rarity: Very rare
Race Requirements: Any elf or half-elf.
Stat Requirements: None.
Legality: Offered by government to selected candidates. Otherwise illegal.
Procedure. Surgery followed by several weeks' recovery time.
Possible Complications. Procedure is fatal for about 5% of adopters. Usually causes sterility.
The Shadar-Kai are an elite Imperial guild of assassins, infiltrators and agents. Elves considered worthy to join undergo this AGM in order to be endowed with teleportation abilities and other benefits suitable to the position. Work on making the procedure function on other races is being done, but has yet to be accomplished successfully.
The procedure changes your race to a Shadar-Kai, and changes your caste to Amber.

GENASI

Rarity: rare
Race Requirements: Human, any elf, half-elf, halfling, goliath.
Stat Requirements: None.
Legality: Offered by government to selected candidates. Otherwise illegal.
Procedure. Surgery followed by several weeks' recovery time.
Possible Complications. Procedure is fatal for about 12% of adopters.
The GENASI procedure (General Enhancement of Arcane and Somatic Intelligence) is a drastic one offered to talented soldiers who are used in elite fighting forces. It attunes the candidate to an element, which they then may use to aid them in combat situations. Unlike other race-changing AGMs, this is a 'genetic' procedure in the true sense of the word; two genasi will parent a genasi child, unlike Kalashtar, who parent children of their original race.
The procedure changes your race to a Genasi, and changes your caste to Amber.

Gills

Rarity: Common
Race Requirements: Any without the ability to breathe underwater.
Stat Requirements: None.
Legality: Legal.
Procedure. Surgery with a day's recovery.
Possible Complications. Almost never. Badly performed procedures carry typical surgical risks.
This procedure is one of the most common AGMs, providing the adopter with a working set of gills. You gain the ability to breathe underwater.

Grungskin

Rarity: Uncommon
Race Requirements: Any race without fur, feathers, or scales.
Stat Requirements: None.
Legality: Legal.
Procedure. Application of a salve once per day over the course of a week. Each time the salve is applied, the adopter must make a DC 12 constitution saving throw. On a failure, they are considered poisoned until a long rest.
Possible Complications. Those with low constitution may become very ill and reject the modification. Deaths are rare. 
This procedure imbues the adopter's skin with grung-like qualities, allowing them to secrete poison at will. You are resistant to poison damage, and you have advantage on saving throws vs the poisoned condition.
As a bonus action, you can secrete poison from your pores. For one minute, any creature that touches you with its bare skin for the first time on its turn, or is touching you at the beginning of its turn, must succeed on a Constitution saving throw. The save DC is equal to 8 + your proficiency bonus + your Constitution modifier. On a failed save, the creature is poisoned until the start of its next turn. Once a creature succeeds on this save, they are immune to the effect until they take a long rest.
While secreting poison in this way, as an action, you can also apply your body’s poison to a melee weapon or up to 3 pieces of ammunition. The poison loses its potency after 1 minute. A creature struck by a weapon or piece of ammunition poisoned in this way must make a Constitution saving throw with the same DC equal to 8 + your proficiency bonus + your Constitution modifier or be poisoned for 1 minute. A poisoned creature can repeat the saving throw at the end of its turn.

Stone Hand

Rarity: Uncommon
Race Requirements: None.
Stat Requirements: Strength 13.
Legality: Legal.
Procedure. 1 hour-long immersion of hand in genetic solution. The hand remains unusable for 1d4 days, after which you regain full movement. 
Possible Complications. There is a small chance that the procedure fails, and the hand never regains movement. The likelihood of this depends on the quality of the solution.
This procedure transmutes the skin of the adopter's hand into another material. Your unarmed strikes now deal 1d6 damage. Other qualities depend on the material. Feldspar and Pyrite are the most common choices:
Feldspar: An extremely durable, opaque, peach-coloured stone. Checks made to escape your grapple are made with disadvantage. You have advantage on Strength saving throws made to hold onto things. You have disadvantage on slight of hand checks. If you are a monk, your Deflect Missiles ability now works with bullets.
Pyrite: This metallic, grey rock is unusually conductive. When you deal lightning damage, you may treat any 1s rolled as 2s. As long as your stone hand is empty, if you take lightning damage, you may use your reaction to make a dexterity saving throw vs the attack roll or the save DC, lifting your hand to absorb the damage. If you succeed, you gain resistance to the lightning damage dealt, and the next spell attack or unarmed strike you make using that hand deals additional lightning damage = 1d10 + your constitution modifier, provided it hits.

Vestigial Wings

Rarity: Rare
Race Requirements: Any race without wings or a flight speed.
Stat Requirements: None.
Legality: Legal.
Procedure: Grafting of lab-grown wings in complex surgury. Usually requires at least a month of bed-bound recovery. 
Possible Complications. There is a high incidence (about 50%) of the rejection of the wings, which usually means they must be removed in surgery, and the procedure reversed. In rare cases, this rejection can cause infections and illness, possibly causing death.
A procedure only for the most dedicated, this highly expensive and risky AGM grafts flightless wings onto humanoids who wish to emulate high aasimar. The wings usually resemble those of the aasimar themselves (feathered), although a recent trend after the visits of the Fey ambassadors has been dragonfly, moth or butterfly wings. The wings are mostly aesthetic and cannot grant a flight speed, but they do sometimes facilitate gliding.
Using your vestigial wings, you may use your reaction when you are falling to slow your rate of descent to 60 feet per round, taking no falling damage and landing on your feet. Once per long rest, as an action, you may make a Strength (Athletics) check to float as if under the effects of the spell Levitate. This effect is not magical and does not expend a spell slot. At the end of each turn, you must make a Constitution saving throw, ending the effect on a failure. The DC of these checks is dependent on the weight of your armour: 14 for light armour, 16 for medium, and 18 for heavy.