same as it was prior just extended for/by cross world. It never effected the DF in the past and I doubt that it will right now. Maybe further down the line that might become an option but right now it's PF only as far as I am aware. Meaning that if you black listed someone (server or cross server) you will see their PF entry grayed out, making you unable to join their party if they are the party leader. That does not apply to parties, that might have been formed by that person prior and the leader ship have been transferred to someone else, in that case you will be able to join the party and while that person won't be able to communicate with you via tell, he/she is clearly visible via party chat and in the group menu. Unless I missed the announcement in the last couple of weeks, that this has changed (sry wasn't much in game), I would stick with that for now.