Hi,

One of my player want to play a Rogue Psyker / Sorceror. I have read the rule but doesn't understand how to use them. How can he be a sorceror at the begining (they start level 2)? Or starting a Rogue Psyker (without the efffect of Trait: Sanctioned Psyker?

The Sorcerer Talent is one with serious prereq's you are likely not going to have at starting level.
If you have Radicals you could work towards Malific Scholar (Adept Class), which is a pretty quick way towards Sorcery.

Or you could simply play the Rogue/Unsanctioned Psyker...simply remove the Sanctioned Trait and replace inappropriate skills and talents.
A Rogue Pysker is of course the favourite for Tainted Psyker (Again Radicals)...

I'm going to assume that you have the Radicals Handbook. Really if you look at a starting pysker there is a lot of XP to work with:

PSI 1 (100xp)

Invocation (100XP)

Psyniscience (100XP)

While being a sorceror requires:

Forbidden Lore Warp or daemonalogy +10 (200XP)

Sorceror talent (200XP)

So if you give up the PSI, Invocation, and Psyniscience that is only 100XP. Or 300XP if you give up only the PSI. The real issue is getting the 35 int and 35 will be hard, but not too hard. They start as void born or blighted schola, and use their remaining XP to buy up int and will. A void born will average 35 for will and 30 for int. While a blighted schola (flat 2d10+10 for all with +5 for will) will average 30 for int, and 35 for will, and will have a full 400XP as they start with Forbidden Lore Warp.

Note that you could do a similar thing for an adept as well, but then you'd need to provide for regular psyker related advances.

For a Rogue Psyker just don't give the psyker the sanctioned trait. Personally I also give a trait I call unsanctioned.

Unsanctioned- The psyker have never been properly trained and conditioned. This makes a psyker stronger, but more dangerous. When rolling to mainfest an additional "rogue die" is rolled. This die must be a different color establish prior to the roll. This die may be used to replace any of the other psi dice, but a roll of 9 on any die (rogue or not)must be counted for determining if a psyker triggers phenomena.

Creatures Anathema has the vermin speaker advance. Rather than being taken by the black ships, the psyker fled into the undesirable parts of the planet where there were only beasts for company.

Dalnor Surloc said:

Actualy they don't. They just tread it as a basic skill, that's all.

Without some serious elite advances it's impossible to gain sorcerous powers before rank 4 (adept) or rank 5 (psyker, diviner or cleric).

With the right amount of xp and DM sponsored elite advances it might be doable by rank 3.

As for the rogue psyker thing, simply let the player's character start without the 'Sanctioned' trait and have him/her be prepared for one hell of a ride.