This is not a boasting-topic. This is something which a lot of farmers out there still need... hope!
This morning, after my 462nd kill, the Raven Lord FINALLY dropped. Call me crazy for running him so many times, call me crazy for actually counting all those times and call me crazy for posting this topic.
But whats more important: It still drops! .. I almost gave up hope!
What worked for me was that I sent every able body into the damned dungeon. I had 4 characters who were 85 or higher and one character who was 80. Now 70 in nice gear CAN work, but it isn't quick. Make sure that every character who is 80 or higher can run the mount for you. Since acount-bound mounts, it doens't matter which character wins the actual mount.
Also try to do it in the morning. That way, you get it out of your system and don't forget it in the evening.
Most of all... my thoughts go out to you people! Don't listen to people who got it on their first run; don't listen to people saying they got all rare mounts in a day. There's nothing else to do but suck it up every day and farm.
So, I know this doesn't get you the mount, but for what it's worth... good luck
mine dropped in patch 4.2 after 87 tries on my mage.
but contratz to you for being consistent, i almost gave up hope on this mount cos i was trying with my other characters as well.(more than 150 times)