Primaris Powers question

[Warsmith Shaughn]

So my buddy and I had different interpretations of how Primaris Powers work, maybe someone here can help?

A level 1 Psyker rolls his one ability off the list for a chosen psychic school. If he decides to keep that ability, does he also get the Primaris for that school in addition to the one he rolled?

[0rph3u5]

See "Psykic Focus", all Psykers which generate their powers from one discipline alone gain that discilpine's primaris. Since a ML 1 psyker can only try one discipline that psyker has the primaris plus the power rolled.

[Warsmith Shaughn]

Thanks, that's how I thought it was. My buddy was playing a lvl 3 demonologist, rolling three abilities, then trading one out for the summoning primaris. Which I guess you can do; but why trade one out when you can get it for free?!?!

[Da Gargoyle]

Is he rolling all three abilities in the same discipline? If not that is why he may want to substitute a power for the Primaris Power. However on pg 23 of the rule book it actually states that if all the psychic powers come from the same discipline then the psyker will already know the primaris power and can not substitute any of his randomly generated powers for it. (Of course he can only substitute a power for the Primaris power from that discipline)