Sorry I've read those boxes and I'm still confused. Normally a Grey Knight gets 1 power per Psy Rating. However because I took Librarian it says I do not follow those rules and can instead buy powers per deathwatch. That leaves me confused as to starting powers. Librarian specialty says I start with 3 powers chosen from specific list. So I choose 3 from that list and can buy more powers (including grey knight powers) later?