Just posted this on the official forums (http://us.battle.net/wow/en/forum/topic/8569860731), just in case anyone is struggling with Lei Shen in LFR:
So I just downed Lei Shen in LFR, and I have a few things I want to discuss about it.
First, hats off to the encounter team. He has really fun and really interesting mechanics, and I like how in ToT in general there are mechanics that let you decide how you wanna do things/what order (kinda like Yor'sahj from DS).
We killed him with 7 stacks of determination. I think we could have easily killed him with less, but people were learning the fight on those first attempts. It was such a huge relief and such a good feeling to kill him. We struggled in Phase 1, and people were leaving constantly, but once we got Phase 1 down people stayed with the group and we meshed really well and got the boss down. It was the longest I have seen people stay after the boss kill. Everyone stuck around and was thanking everyone and generally just being happy. It was what I feel that LFR should be, and it was a high point with the WoW community.
I realized during this fight, that now more than ever, an in-game Voice Client is becoming necessary. It was really tedious typing out all of the mechanics. We spent a good 30 minutes worth of time just discussing tactics via chat, that would have been 5 minutes in a Voice Client and saved us a lot of confusion. There are definitely some hurdles to overcome, and some logistics to work out (like how to you monitor/protect against harassment) but I would love if LFR end bosses had this difficulty, and I could talk to my teammates about the strategy. Maybe make it so by default most people can just listen, because I know a lot of people don't have mics or are nervous about talking, but almost everyone can listen.
A few tips if you are struggling:
If you are a tank, you MUST know the mechanics of the fight. The tanks have a big job this time around, and you can't fake your way through it. YouTube is a great source for fight videos. The 15 minutes spent watching the video will easily save you more than 15 minutes worth of wipes.
The mechanics are critical. Execute the mechanics over doing extra DPS/HPS. There is no Enrage timer, just a Soft Enrage in Phase 3 (which was the easiest Phase I think), so play it safe.
The raid leader needs to lead the raid. This sounds kinda derpy, but in most LFRs the raid leader doesn't do much. Not the case for Lei Shen. Mark targets, mark people, call out raid warnings, be active, and leading your team to victory will feel amazing.
Write some Raid Warning macros, so you can call out important mechanics with a button push instead of typing them (again, this is why I want a nice Voice Client). Once I wrote a few of these between pulls, our Phase 1 execution went from atrocious to amazing.
Don't be afraid to use a vent server if you have access, at least a few people can coordinate.
Overall, stick with it, learn the mechanics, work together, be patient, be understanding of mistakes as long as they are corrected the next attempt, and I promise you the kill will feel awesome when it comes.