I've been trying to figure out what exactly happens when an Idolotrix Magi of Tzeentch gets either the Mark of Tzeentch or Warpsmith rewards. Both increase Psi Rating, however the Idolotrix entry says that their Psi Rating is limited by their Corruption Bonus.

Lets say you have an Idolotrix Magi who has been keeping up with his Psi-Rating as his Corruption goes up. Hes at Psi Rating 3. He gets a new Gift of Tzeentch and rolls Warpsmith, presumably he raises his Psi Rating to 5, or does he bank 1 rating until his corruption goes up ten more points?

Furthermore, and on a somewhat unrelated note I have another question:

If you finish qualify for a Gift of the Gods before you finish Character Gen do you get to pick the Gift or do you roll it randomly as per gaining it in play?

Ramaloke said:

Well, I'd definitely rule it as they are gifts from the god of Change they definitely don't comply with "traditional rules" for psykers, so they come into effect immediately. It just means that he can't raise his psy rating any further until he has gained more corruption.

You roll the Gift normally, of course. Mutations are by their very nature random and non-negotiable(altho you can sacrifice Infamy to change the result up or down).

It even states so in the psychic powers section in the book. Also I think that if he gets mark of tzeentch, he becomes somewhat more standard psyker and can have psy rating of CB+WPB but that's how I see it.