Few are probably looking back at Ulduar now, but Vortex is pretty bull-headed when it comes to achievements (we do have a large number of tauren, after all). Lacking both a rogue (wound poison, misdirect) and a hunter (misdirect... he's currently vacationing in the Bahamas!), we finally forced our way through Yogg's defenses with no assistance from the keepers.
I covered both the basic Yogg Saron strat and One Light in a fair amount of detail. For the truest form of hard, however, take One Light and nix Thorim's 10% damage and 20% health buff, with no chance of actually killing the adds in phase 3 (thus having them constantly beating on your less-health-than-otherwise tanks).
It is tough, as one would expect. It all comes down to controlling the P3 adds around their shadows healing buff, aggro on healers, damage on the tanks, and burning down Yogg as fast as possible. ICC gear helps, even the ten-man stuff, for making up for the lack of wound poison and misdirects. Your entire raid needs to be on their toes and ready for anything. Getting through P1 and P2 is the easy part... not much change from One Light, aside everyone being squishier. It's P3.
Phase 3 Alone:
Your brain team should get Yogg down to 30% within 2-3 portal phases. With current iLevel 232-251 gear, it should only take 2 phases, assuming all goes well in the brain room. Topside team should be clearing all tentacles and running to the back of the room before the brain team pushes Yogg into P3: use voice chat to coordinate this.
- 2 Healers: run all the way to the wall. I mean ALL the way to the back wall: hug that wall so tight you leave claw marks. A holy paladin, even an offspec gimpy ret, is a major boon here with beacon of light. We used a holy pally and a resto druid. Keep full hots/heals/shields/etc running on both tanks and keep them both alive as long as you can, because when one of them dies, YOU are most likely going to die next.
- 2 Tanks: position yourselves between Yogg and your cowering healers. Make SURE you are in range of both healers, but spread yourselves out to minimize Empowering Shadow heals. Use every cooldown you have to keep yourselves alive. Trade off with each other picking up each new add spawn, and make sure you get them before they reach your healers. The longer the both of you stay alive, the longer the raid has to kill Yogg before he wipes you all out. When one dies, be ready to mass AoE taunt the other tank's adds to eek out a few more seconds for the raid.
- 6 DPS: burn Yogg. Ignore the adds and just burn the back of Yogg's head. Make sure you turn away from skulls, of course, but your job is to get Yogg down as quickly as you possibly can before the adds overwhelm your tanks.
Want a video of the chaos? Check out Vortex's 10-man video on Filefront (click to stream if you'd prefer!). It is from a warlock (topside team) point of view.
An edited version is hosted on YouTube as well, though lower quality.