The Secondary Heart, also called the Maintainer, is the first and least difficult of the 19 Astartes gene-seed organ implants a Space Marine neophyte receives to transform him into a full Astartes. It resembles a smaller version of the Human heart and is implanted in the chest cavity and connected to the rest of the neophyte's circulatory and pulmonary systems near the original heart. Its function is to enhance the performance of an Astartes by supplying more oxygen and nutrients to the muscles by increasing blood flow well-beyond that capable for even the most fit normal Human being. The Secondary Heart can often save an Astartes' life in combat. In the event of combat damage to or failure of the Space Marine's original heart, the Secondary Heart is usually capable of pumping enough blood through the Astartes' circulatory system to maintain survival until he can be treated by the Chapter's Apothecaries.

Once per long rest when you are reduced to 0 HP but not killed outright, on your next turn electricity surges through your body and jolts you back to consciousness; instead of rolling for a death saving throw, you automatically gain 1 HP.

The Ossmodula, also called the Ironheart, is the 2nd gene-seed organ received by a Space Marine neophyte. This implant, surgically placed alongside the neophyte's pituitary gland at the base of the brain, thus becoming a part of the Space Marine's endocrine system, secretes a specially engineered form of Human growth hormone. When the effects of this hormone are combined with a diet laced with microscopic ceramic-based minerals, they act to synthesise the rapid growth of an Astartes' skeletomuscular system which results in an Astartes' superhuman strength and massive size compared to a baseline Human male. Two Terran years after the surgery to implant the Ossmodula is completed, the neophyte Space Marine's skeleton will be larger and exponentially stronger than a normal man's with growth having topped out at around 7-7.5 Terran feet (2.1 - 2.3 metres) in height with an equivalent amount of skeletomuscular mass. During this time the rib cage will fuse into a solid mass of bullet-proof, interlaced bone plates. The resulting structure protects the Space Marine's organs from damage in a way the normal Human skeleton never could, though at the price of producing greater difficulties for the Chapter's Apothecaries when they must perform surgeries on a Space Marine's body cavity.

You gain a resistance to all bludgeoning, slashing, and piercing attacks from nonmagical weapons. Additionally, instantly killing you requires twice as much damage as normal.

The Biscopea, also called the Forge of Strength, is the 3rd gene-seed organ to be implanted. It enhances a Space Marine's physical combat ability and survivability to superhuman levels should he live to become a full Astartes of a Space Marine Chapter. This organ is implanted into the chest cavity. It is small, approximately spherical and, like the Ossmodula, its primary action is hormonal. The presence of the Biscopea stimulates muscle growth throughout the body, greatly increasing a Space Marine's physical strength. It can be implanted at the same time as the first two organs, the Secondary Heart and the Ossmodula, generally between the 10th and 12th standard years of age of the neophyte.

While you are a medium-sized creature, you are considered one size larger for grapples and when determining carrying capacity.

The Haemastamen, also known as the Blood Maker, is the 4th gene-seed organ. Once implanted into a main blood vessel like the aorta, femoral artery or the vena cava, the Haemastamen alters an Astartes' blood's biochemical composition to carry oxygen and nutrients more efficiently. The actions of the Haemastamen turn a Space Marine's blood a brighter shade of red than that of normal Humans because of its greatly increased oxygen-carrying capacity. It also acts to biochemically regulate the actions of the 2nd and 3rd gene-seed implants, the Ossmodula and Biscopea.

You still need to breathe air, but you are able to sustain yourself on far less of it (as little as 5% oxygen content) and can hold your breath for 10 times as long as normal. 

 Larraman's Organ, also called the Healer, is the 5th gene-seed organ. Shaped like the Human liver but only the size of a golf ball, this gene-seed organ is placed within the chest cavity and manufactures the synthetic biological cells known as Larraman Cells that were named after one of the researchers in the Emperor of Mankind's gene-laboratories on Terra where the gene-seed for the first Space Marines was created under the Emperor's direction from His primarchs' DNA. These biosynthetic cells serve the same physiological purpose for an Astartes as the normal Human body's platelets, serving to clot the blood lost from wounds, but act faster, more efficiently and more effectively. When a Space Marine is wounded and incurs blood loss, Larraman Cells are released by his circulatory system,attached to the body's normal leukocytes (white blood cells). At the site of the injury, they form scar tissue in a matter of seconds, effectively preventing massive blood loss and infection of the wound. The action of this organ is one of the reasons that the Space Marines are seen as nearly invincible and so difficult to kill despite the terrible wounds they sometimes endure.

Once per long rest as a Bonus Action, you may regain 1d10+Con Hit Points. Additionally, you regenerate 1 hit point every minute. When reduced to 0 hit points you automatically stabilize unless you have suffered a mortal wound (such as instant death from decapitation, evisceration, or massive damage). While at 0 hit points you remain conscious but are incapacitated unless specified to be unconscious by the GM.

The Catalepsean Node, also called the Unsleeping, is the 6th gene-seed organ. This is implanted into the back of the cerebrum, just above the brain stem. When deprived of sleep for a long period of time, the Catalepsean Node "cuts in" upon detecting a rise in the Astartes' stress and fatigue hormones. This allows the Astartes to consciously "switch off" sections of the brain sequentially while remaining awake and alert. This ability comes at a price, as prolonged use of this ability can be hazardous, possibly inducing hallucinations or even psychosis. This implant bears a resemblance to an ancient scientific theory as to how cetaceans known as "Bottlenose Dolphins" "sleep": shutting off sections of their brain while remaining awake and alert through the active use of the other sections. Yet even the mighty Space Marines cannot go too long without actual rest. The longest any Space Marine has ever been on active combat duty without rest is 328 solar hours, achieved by a squad of the Crimson Fists' Kill-team during the battle against the Orks for Rynn's World.

You need no more than 4 hours of sleep to complete a long rest, and gain a (nonstackable) +5 passive perception for two days after sleeping. You may also ignore your 1st level of exhaustion for up to 14 days.

The Preomnor, also called the Neutraliser, is the 7th gene-seed organ. The Preomnor is essentially a second or "pre-stomach" spliced into the Human digestive system above the original stomach that allows Space Marines to eat otherwise poisonous or completely indigestible materials. The Preomnor is capable of biochemically analysing ingested materials and neutralizing most known biochemical and inorganic toxins, and many others that remain unknown save for their toxic effects. Deadly poisons are either neutralised or isolated from the digestive tract by the Preomnor. The Preomnor can also be isolated from the rest of the digestive tract to deal with particularly toxic substances that a Space Marine may simply vomit back up later. Often these extracted toxins are rerouted and then molecularly stored in the Betcher's Gland for future usage by the Astartes.

You gain resistance to poison damage and advantage on saves against any ingested poisons and diseases.

The Omophagea, also called the Remembrancer, is the 8th gene-seed organ. The Omophagea is implanted into the spinal cord and then wired into the central nervous system so that it is directly attached to the cerebral cortex and to the stomach. It allows the Astartes to gain part of an individual person's or creature's memory by eating its flesh. This special organ is implanted between the thoracic vertebrae and the stomach wall and is designed to absorb information and any DNA, RNA or protein sequences related to experience or memory. This implant thus allows a Space Marine to literally "learn by eating." Four new nerve bundles are also implanted connecting the spine and the stomach wall. The Omophagea transmits the gained information to the Astartes' brain as a set of memories or experiences. This enables the Space Marine to gain information, in a survival or tactical sense, simply by eating an animal indigenous to an alien world and then experiencing some of what that creature did before its death. It is the presence of this organ that is responsible for the various flesh-eating and blood-drinking rituals for which certain Space Marine Chapters are famous, as well as giving names to Chapters such as the Blood Drinkers and Flesh Tearers. Over time, mutations in this implant's gene-seed have given some Chapters an unnatural craving for blood or flesh.

You are able to absorb genetic material by consuming blood or flesh, the omophagea inside your body transmitting the gained information to your brain as a set of memories or experiences. What this can reveal is at the discretion of the GM.

The Multi-lung, also called the Imbiber, is the 9th gene-seed organ. The Multi-lung is a third lung implanted into an Astartes' pulmonary and circulatory systems in the chest cavity that is able to absorb oxygen from environments usually too poor in oxygen to allow normal Human respiratory functioning. Breathing is accomplished through a sphincter implanted into the trachea, allowing all three lungs to be used at full capacity. In toxic environments, a similar muscle closes off the normal lungs, thus oxygen is absorbed exclusively by the Multi-lung, which then filters out the poisonous or toxic elements. The Multi-lung has highly efficient toxin dispersal systems.

You are able breath under water for up to an hour before needing to surface and gain resistance to inhaled poisons, gases and diseases. You also have advantage on saves against such things.

 The Occulobe, also called the Eye of Vengeance, is the 10th gene-seed organ. This implant sits at the base of the brain after being implanted along the optic nerve and connected to the retina, and provides hormonal and genetic stimuli which enable a Space Marine's eyes to respond to the optic-therapy that all neophytes must undergo in their Chapter's Apothecarium. These procedures, in turn, allow the Chapter's Apothecaries to make adjustments to the growth patterns of the eyes and their light-receptive retinal cells. The result is that Space Marines have visual acuity that is far superior to that of baseline Humans and they can see in low-light conditions and near-darkness almost as well as in bright daylight.

You have darkvision up to 30ft. You can see in dim light within the radius as if it were bright light, and in darkness as if it were dim light. You can’t discern colour in Darkness, only shades of grey.

The Lyman's Ear, also called the Sentinel, is the 11th gene-seed organ. Not only does this implant's improved inner ear structure make a Space Marine immune to dizziness or motion sickness but it also allows Space Marines to consciously filter out and greatly enhance certain sounds over the capabilities of normal Human hearing. The Lyman's Ear completely replaces one of a Space Marine's original ears. It is externally indistinguishable from a normal Human ear in size and shape. Lyman's Ear is named after one of the scientists who worked in the Emperor's gene-laboratories on Terra in the 30th Millennium who aided in the project to produce the first primarchs and Astartes using the Emperor's own genome as the starting point.

You gain advantage on Perception checks to do with hearing and save against deafness. Furthermore, you gain immunity to any type of dizziness or motion sickness

The Sus-an Membrane, also called the Hibernator, is the 12th gene-seed organ. Initially implanted within a neophyte's cranium, this membrane eventually merges with the recipient's cerebrum, becoming a full part of his neural architecture. The organ's functions are ineffective without follow-up chemical therapy and training by a Chapter's Apothecaries, but with sufficient practice and instruction a Space Marine can use this implant to enter a state of suspended animation, consciously or as an automatic reaction to extreme trauma, keeping the Space Marine alive for Terran years, even if he has suffered otherwise mortal wounds. Only the appropriate chemical therapy or hypnotic auto-suggestion can revive a Space Marine from this state. The longest recorded period spent in suspended animation was undertaken by Battle-Brother Silas Err of the Dark Angels Chapter, who was revived after 567 standard years in Sus-an hibernation.

This organ is also known as the hibernator implant.

When a space marine fails its last death save, make a constitution save DC 20, if passed the space marine does not die but may become dormant in a kind of stasis that can last for hundreds of years. You are unconscious and with the aid of a Techpriest Biolagus you may be revived with a Medicine check DC10 + 1 for every 10 years the body has been in this stasis.

 The Melanochrome, also called the Skinshield, is the 13th gene-seed organ. This hormonal implant is attached to the Human lymphatic system and controls the amount of melanin in a Space Marine's skin. Exposure to high levels of sunlight will result in the Astartes' skin naturally darkening to compensate. It also protects the Space Marine from other forms of electromagnetic radiation. Different levels of radiation cause variations of skin colour in different Chapters due to mutations in the Melanochrome organ's gene-seed. This can be related to the unusually pale skin of the Blood Angels and their Successor Chapters and the dark black skin and red eyes of the Salamanders.

You gain Resistance or advantage on saves against effects done by UV rays and Radiation damage.

The Oolitic Kidney, also known as the Purifier, is the 14th gene-seed organ. It is implanted within the new Astartes' abdominal cavity and it becomes a part of the Space Marines' excretory system, an emergency detoxification organ that allows a Space Marine to survive exposure through the respiration, tactile contact or ingestion of poisons, toxins and gases that are too powerful for even his rugged immune system to normally process without this organ's help. However, this detoxification process renders the Astartes unconscious once it begins, so it can be very dangerous if required during combat. Under normal circumstances, the Oolitic Kidney also acts as a regulatory organ for the Astartes' physiology, maintaining the efficient action of the Space Marine's advanced circulatory system and the proper functioning of his other organs, implanted or natural.

As an action, you may use your entire turn to remove any poison conditions or effects produced by a poison or venom.

The Neuroglottis, also called the Devourer, is the 15th gene-seed organ. It is implanted within the Astartes' upper nasal passages and after it is functioning, chewing, tasting or smelling a substance allows a Space Marine to biochemically test it for toxicity and nutritional content, essentially determining if the substance is edible or poisonous. The organ also allows the Space Marine to identify extremely subtle odours with the same fidelity as the average canine bred for tracking, allowing him to even track his quarry by smell or taste alone.

You gain advantage on Perception or Investigation checks using smell or taste. You additionally gain advantage on intelligence check to identify any chemicals in a mixture that you ingested.

The Mucranoid, also called the Weaver, is the 16th gene-seed organ. It is implanted within the central nervous system and responds to specific chemical stimuli in the environment, causing the Space Marine to secrete a waxy protein substance similar to mucus through his pores that seals his skin. The gland's operations must first be activated by external chemical treatment, usually self-administered, before it will activate. Space Marines are cocooned in this way before they enter suspended animation, and the process can even protect them from the harshness of the vacuum and other extremes of temperature, particularly deeply frigid environments.

Once per long rest, an apothecary or Tech Priest Bioligus may activate to provide resistance to the effects of a vacuum, as well as  Radiant and Cold damage. This last for 24 hours.

The Betcher's Gland, also known as the Poison Bite, is the 17th gene-seed organ. Consisting of two glands that are implanted into multiple locations inside a Space Marine's mouth, including the inside of the lower lip, in the salivary glands or in the hard palette, these two glands working in tandem transform an Astartes' saliva into a corrosive, blinding acid when consciously triggered. This allows a Space Marine to spit a wad of corrosive acid with the effect of blinding, wounding or even killing an enemy outright. These implants' more common use is to aid in the digestion of unusually difficult or impossible things to digest, such as cellulose. In the gene-seed of several primarchs, like that of Rogal Dorn, this organ has atrophied and is no longer as effective or has simply ceased to function entirely in the Astartes of the Chapters that use those primarchs' gene-seed.

As a bonus action, you spit your corrosive saliva at a creature within 15 feet. It makes a Constitution saving throw (DC 8 + your proficiency bonus + your Constitution modifier) or is blind until the end of your next turn.

The Progenoid Glands, also known simply as the Gene-Seed, are the 18th organ. Every Space Marine has a pair of these organs, one implanted in the neck and another in the chest. The organs hormonally respond to the presence of the other Astartes gene-seed implants in the body by creating germ cells with DNA identical to that of those implants through a process very similar to cellular mitosis. These germ cells grow and are stored in the Progenoid organs, much like sperm cells or egg cells are stored in the testes and ovaries of normal men and women. When properly cultured by the Apothecaries of a Space Marine Chapter, these germ cells can be gestated into each of the 19 gene-seed organs needed to create a new Space Marine. Thus, for most Astartes, their Progenoid Glands represent the only form of reproduction they will ever know, though the DNA passed on will be that of their primarch, not their own. Mature Progenoid organs can be removed and new gene-seed implants artificially cultured from them. This is the only way new implants can be created, so a Chapter depends upon its existing Space Marines to create other Space Marines. Five standard years after implantation, the Progenoid Gland in the neck contains mature gene-seed and may be removed and its germ cells harvested, while the larger chest Progenoid is not considered ready for harvesting until 10 standard years have passed. The harvesting is normally done after an Astartes' death by an Apothecary, who carries a special attachment on the mobile medical field kit he carries on his arm known as a Narthecium. This attachment is called a Reductor and it is specifically used to extract both Progenoid Glands from the body of a slain Astartes so that his gene-seed can be used to replace the Chapter's loss, the only form of true immortality that Astartes will ever know.

The Black Carapace, also known as the Interface, is the last and one of the most important of all the 19 gene-seed organ implants a Space Marine neophyte will receive as he is transformed from a normal, adolescent Human male into a superhuman Astartes. This neuroreactive, black organic fibrous material is implanted directly under the skin of the neophyte's torso. Points are then cut through the Carapace by an Apothecary using surgical tools that allow a Space Marine to directly interface his central nervous system with his Power Armour's cybernetic systems. After a few solar hours, the material hardens and invasive synthetic fiber bundles that will serve as connection points for neurons grow inward and interlink with the newborn Astartes' central nervous system. Note that a Space Marine needs the Black Carapace to use his Power Armour to its maximum capabilities, but the armour itself does not need this implant in order to function. 

You take no disadvantage to dexterity while wearing power armour.

The Astartes are physically stronger, far more resilient and often mentally far removed from the lot of most normal human beings. In the presence of the Astartes, most people feel a combination of awe and fear, and many cultures on the more primitive worlds simply worship them outright as demigods or angels of the God-Emperor made flesh.

They should feel so, for many Space Marines feel little compassion for those they have sometimes termed "mortals" in comparison to themselves, seeing the very people they were created to protect as little more than obstacles to a more efficient eradication of the Imperium's enemies.

Your Strength, Dexterity, and Constitution scores increase by 2, and their maximums increase by 2. Your Intelligence, Wisdom, and Charisma scores increase by 1. Additionally, your unarmed strikes deal 1d4 bludgeoning damage and you gain proficiency in Athletics and Perception. You are proficient with all armour and weapons.

A Space Marine is more than just a Human being with extraordinary powers. Just as their bodies receive 19 or 22 separate gene-seed implants, so their minds are altered to release the latent powers that lie within all Human minds, and these are not the psychic powers of the Warp but the intrinsic capabilities of every Human brain. These mental powers are, if anything, more extraordinary than even the physical powers endowed by the gene-seed implants. For example, a Space Marine can control his senses and nervous system to a remarkable degree, and can consequently endure pain that would kill a normal man. A Space Marine can also think and react at lightning speeds.

This indoctrination also includes psychological conditioning which is intended to reinforce a Space Marine's respect for authority and his willingness to follow orders regardless of his own desires, as well as to harden his mind to the corruptive temptations offered by Chaos. It is no exaggeration to say that many Astartes truly no longer know fear. At the end of this process, if all goes well, an adolescent Human male will have been transformed into a superhuman Astartes. Yet, in many ways he will no longer truly be Human, having sacrificed his own Humanity so that he might protect that of others.

You have advantage on any saving throws made to resist the Frightened or Charmed conditions.

You can speak, read, and write Gothic and one extra language of your choice. Like Humans Astartes typically learn the Languages of other peoples they deal with, including obscure dialects. They are fond of sprinkling their Speech with words borrowed from other tongues: Orc curses, Aeldari expressions, Squat Rigger talk, and so on.