I wonder if the kill ranks as X class milestones are related to when we stopped getting credit for fireteam kills on those cards. For example, I've got 900 crucible kills as a warlock, and never played a single crucible game with my warlock. I also had 500ish as a titan before finally jumping in with that class. I'm over 1100 now as a titan, and grimoire score did not change when I hit the 1000 kill milestone. I should roll back into crucible and get enough so "I" have actually killed a 1000 players in crucible to see if the girmoire score changes then.