Rather than bump the older thread (is 20 days old?) I'm just going to post my strategy here in hopes someone uses the search function.

So last weekend I got my DK team up to 85 and AV weekend was very good to me so I entered Ulduar in full Ruthless. Three DKs are frost, one of them speced blood with one Holy Paly. Gear is full Ruthless so no PvE gear at all. I was able to do most of the bosses and their hard modes without any issues. I'm still working on killing Yogg and Agalon without outside help.

Anyways Vezax is an annoying fight not because of he cuts off mana regeneration but because he casts Mark of the Faceless. Since I run a melee team this meant he healed for 150,000 every second each time he casted it. I tried a few strategies, but the one that worked the best was placing two Death Knights outside of melee range:

DK4
DK1 Vezax DK2
DK3
Pal.5

I disabled IWT on DK1 and 2 and the net result was I effectively two manned the boss. DK4 stays far enough away from the tank so that if he gets Mark of the Faceless, it doesn't heal Vezax. My Blood DK was able to heal through much of the damage with the occasional heal from the pally or Draenei racial. During my kill attempt, the Holy paly actually spammed the tank and sat at zero mana so I imagine with proper healing, the fight would be trivial. Also, remember to kill one of the saronite vapors if you don't want hard mode.

Thorim:

I first thought this fight would be impossible since you need to split the party. In reality it was very simple: I sent two dps dks in the tunnel, and left the healer, tank and dk3 in the arena. I dropped my aoe effects in the arena and then focused on the gauntlet, swapping back to the arena every time I killed a mini boss. After Thorim is down the fight is a simple tank and spank



I'm still working on Yogg, and if anyone has any advice, please leave it here.