This perk is not available during level up, but rather must be purchased. The PHOENIX Monocyte Breeder may be purchased from Doctor Usanagi at the New Vegas Medical Clinic for 12,000 caps, through the use of an auto-doc. It is designed to gradually heal damage over time.
The PHOENIX Monocyte Breeder speeds up the regeneration of cells with in the user's body, similar to that of a lizard or sea creature, allowing for a quicker healing of wounds.
- In Hardcore Mode, sleeping on a bed you do not own (or did not rent) does not heal the player, and thus consumables are the only source of healing; with this perk sleeping and waiting will heal based on the equivalent in real-world seconds to the in-game time passed. Fast-traveling will also heal the player for the estimated amount of game-time that the player travels through. Therefore, the healing rate is almost instantaneous, save for the loading sequences between each fast-travel.
- Since it takes so long to fully heal the player, this effect is only valuable outside of battle.
- Players will find that this implant is very useful during the Dead Money add-on because of the short supply of stimpaks.
- Waiting 1 in-game hour will restore 12 HP.
- Individual limb health is not affected by the regeneration; these must still be healed by normal means.
- The Scorched Sierra power armor, which is only obtainable in the add-on Lonesome Road, provides a more noticeable healing effect of 2 HP per second.
- Having the Solar Powered and the Rad Child perk with this perk makes you have an inhuman healing factor, healing fatal wounds in mere seconds. Adding the rad regeneration perk will further your healing. Your limbs will take damage but will always heal. With all these perks you character becomes practically immortal.
 Behind the Scenes
- Monocytes are a form of white blood cell (leukocytes) which react to inflammation signals and differentiate into infection-fighting cells to protect the body from disease.
- "Phoenix" is probably a reference to the Greek mythical firebird. Most accounts say that the bird was an immortal creature: at the time of death, it would ignite, burn to ashes, and be reborn from them.
- "That's the PHOENIX Monocyte Breeder. The implant speeds up cell regeneration, an effect similar to that of some lizards and sea creatures." - Dr. Usanagi