Editing Gene-seed (section)

==== Thousand Sons (XV Legion) ====
{{Main|Thousand Sons}}
* Increased chance of bringing out psychic powers, as well as amplified psychic power.
* Recipients subject to a high rate of mutation, called The Flesh Change; unstable.
The most unstable genome in the Space Marine legions, the Thousand Sons suffer from the Flesh-Change, a problem that caused Thousand Sons to mutate spontaneously. [[Magnus the Red]] fixed it, with some "[[Just as Planned|help]]" from [[Tzeentch]]. After the [[Horus Heresy]], the flesh-change came back with a vengeance. [[Ahzek Ahriman]] tried to fix it with his Rubric, and he did end up stopping the flesh-change... by turning all non-[[psyker]] Thousand Sons into dust; sorcerers also had their powers enhanced in addition to no longer suffering ill-effects from the Flesh-Change. So while theoretically, the Sorcerers of the long suffering Legion can provide gene-seed, in practice, it's corrupted so often that few will ever make new Marines. Thousand Sons specifically hunt for healthy and stable psyker boys to implant them with their oh-so-rare gene-seed to ensure the recipient would become a sorcerer. If "Masters, bidding!" TS character words to be trusted, Thousands Sons found a way to implant their progenoids into grown up men (so they can teach and test them for longer before implantation), and perform a scaled down Rubric on them to prevent the Flesh Change. According to Phil Kelly they also replenish their numbers by summoning back souls of destroyed Rubrics, and Magnus supposedly can bring back Sorcerers he isn't pissed off at, so gene-seed wouldn't matter much to them. It is known that Magnus the Red used his knowledge of Biomancy to turn his mentor Amon into an Astartes despite his old age, so its possible this technique was passed down to his Legion.