Board Thread:Warhammer 40k General Discussion/@comment-14745711-20130906234048/@comment-25177957-20140908160703

It takes around 1 hour to a day for a perpetual's injuries to heal. Furthermore, the Emperor had basically faced the Dark gods all manifested in Horus, which injured him enough to stop his perpetual abilities for a short time. Since we only know Vulkan was a perpetual Primarch, then it's doubtful it came from the Chaos gods, since they would have given the traitor Primarchs perpetual abilities in order to win the galaxy for Chaos in the future (Unless Tzeentch was too lazy that day to scheme ahead).

All Primarchs had a tinge of psychic ability, sure they weren't active and practicioning psykers like Magus The Red or Lorgar, but they still had psychic ability, which came from the Emperor. And psychic power is the only thing that can allow a being to take advanatage of their perpetualism, since it's not a physical or natural occurance. (I'm quite sure powerful Eldar psykers such as Eldrad Ulthran were also perpetuals.)