Sadly sometimes that does not work cause a you get a troll off-tank or b he just does not want to listen.
Let me tell you a story, granted we were almost getting him but that does not make what happened to me less of ideal.
Yes it is possible to solo tank norushen, but with my inexperience in doing so on my alt at that time which had not tanked since ToES N/MSV HC earlier this expansion I was not too keen on doing it.
DPS was not the highest the top averaged on 130k and the bottom half on 70k with me on 267k due to the massive amount of vengeance I had in the end.
That meant when we wiped it was around 1min to berserk with 5% health left on boss.
But basically the other tank went in as tank. I could tell cause he was a blood dk as me and was in blood presence. But I pulled with all my cooldowns like I normally do. Whispered the other tank before pull to taunt on 4 or whenever he went came back from inside. Yet the taunt never came. And for some reason I never got forced into the realm. So over the duration of the boss fight I kept spamming taunt in whisper/raid/say/yell and raid warning but nothing happened. I then finally died in the end with 37 stacks cause I could no longer keep myself up and ran out of defensive cd's.
But the worst thing was yet to come. When I died the other tank did not even get aggro. It was a random dps. So not only did he not taunt he did not even attack the boss. The only thing he did was to collect the spawning add (which I also did whenever I could with deathgrip.)
After the wipe I asked out in raid why he did not taunt. And his response was following: "I never 2 tank this fight cause it is not needed and the group we are in is kinda bad so I dont wanna put in any effort" (in a whisper) I then proceeded to say that the dps was not as high that one would hope so that if we wanted to kill this boss I needed him to taunt.
Sadly he then wrote out in in raid and said that I was a bad tank for not being able to solo tank it in 501 ilvl gear (mainly normal terrace and hc msv gear).
I then proceeded to get kicked cause who knows why.
I hate tanking lfr But since people don't want my dk in flex or my main priest I have to try get as much gear there.
I am currently 547 ilvl in tanking on dk and 543 in healing. Only time ill be doing those is with guild. when they do.
I hate lfr but I am forced to do it cause the elitesjerks out there who requires 550+ to join flex.