i have opened today my 14th. cache and still no essence (really annoying cuz only the last nazjatar healer essence missing)
Yes, the 2.4k rating is indeed the hardest part of this achievement and probably the only big wall for most people. PvP is completely broken and unfun meanwhile. You CAN get the rating with every spec, no question about it, but it's a lot harder when you aren't playing one of these meta PvP specs (or tank *lol*) with the right corruptions and mates. Even a boost here is much more laborious like buying an Azshara kill. I also don't know why the r4 essences will be removed with SL, but gratz to everyone with this achievement.