Actually Magnus unintentionally (not sure if thats spelled right) brought into Tzeentch's service, nevertheless there are no Immortal Loyalists since there Emperor isn't even Immortal.
The Emperor was immortal, but it depends on your meaning. He has been alive since the ancient days of earth, and is still alive in the 41st millennium. He was immune to aging but not to damage, just like the primarchs.
They live out their life and die, they just get reincarnated with all their memories intact if memory serves me right. Just like the sages that killed themselves to make the Emperor, they just lived life then reincarnated to live it again.
I thought they were immortal, like they have crazy regen to the point where Vulkan can regen burning up in atmosphere.
Oh sorry should have been more clear, I know the Emperor is immune to aging (Not sure if that's because of the thousand souls a day thing or if that's what he needs to survive each day idk) anyway I did mean immunity to damage, since Demon Princes can never die they only get banished back to the Warp for a short time.
I challenge you to a duel of honor for the privilege of sending this heretic scum back to the hell his dark gods have made for him.
