so you already come with the primaris for the nurgle disciplines for both csm and deamons. that is a specific rule for them so a lvl 2 sorcerer would still get to roll 2 power from another discipline. and in order to get the free primaris those power's have to be from the same discipline. so if you take 2 powers from say biomancy then you would also get the primaris as you took all of your actual power's from the same discipline. the nurgle power is basically a free power or am i interperating this incorrectly?