Raegwyn and his friends were able to kill Blackhand on Heroic difficulty with only using death knights. Quite an impressive achievement, since it's still the hardest boss fight in the game on this difficulty.
Even though Blood Death Knights are tanks, their self-healing and their damage is good enough to survive and finish the fight in time. All ten are specced as tanks, but only one of them is tanking at the same time while the rest do damage. When the active tank is about to fall,they switch roles, and someone else takes care of the job and eats up the damage.
Here's how the fight went down:
What made this boss so ridiculus awesome and difficult was that everyone could get any ability all the time! Normally tanks dont get targeted by impale... for good reasons. But since we didn't have dps or heals we all got it all the time. It's impossible to assign ppl to do stuff when everything is completely random. This means you can get an impale and have to run behind the siegetank, while you are tanking the boss or kiting the siegetank, which is quite nuts. Or look what happened to me in the last phase. Mine then impale then taunt boss then another mine AND impale then another impale trololo. This boss really was nuts. It still went much smoother than expected due to my Deathnerds being awesome.
They're about to try Warlords of Draenor's other raid Highmaul on Mythic difficulty with twenty death knights. Good luck!
(Don't worry non-DK tanks, warriors will get a buff in the upcoming 6.2 patch.)