Here you go.
Time for Plague wing dps DK optimization!
As you know, my personal rule is to only blog on maximizing performance when I have at least a couple kills under my belt. I HAVE been able to kill Putri's pets, the putrescent Rotface and Festergut a good number of times now, so you get to hear about them!
Both of these bosses have different challenges that may pose different difficulties for various guilds, but I'll pick Festergut for now, as this the one Insomnia has had the easiest time with.
Festergut is essentially a tank and spank fight, with fairly tight dps requirements. If your guild doesn't have full T9 with some Icecrown gear, it may be difficult to complete the encounter in time.
Pull/Phase One: Run in with the tank and park it in Fester's bilious behind. Summon Army pre-pull and set them on Fester right away. As soon as your attack power procs are up, use your pet cds. You should have a chance to re-use them once more before the end of the fight. Your job, should you choose to accept it, is to dps your merry heart out! As usual, I assume you know the basic rotations/priority for your spec, so get to it! Besides hitting Fester as much as humanly possible (or orcly possible, as the case may be), there are only a few other events that you need to be aware of. Gas Spore: Normally, a spore will be on the melee, and you just stand there and get inoculated while dpsing. On the rare occasion, however, two melee may get a spore, and if one of them is you, you may need to run out to ensure ranged/healers get inoculated. Just know your assignments on this one.
Pungent Blight: Festergut releases the gaseous blight violently. :) As long as you've been inoculated, don't worry - it won't really hurt you! Even if you haven't been inoculated, you are one of the few classes that can survive this event without help. Just pop Anti-magic shield and Icebound Fortitude and as long as your health is topped off, you should be fine. I pop AMS for Pungent Blight anyway, as it's free runic power for more Death Coils. Don't worry about Vile Gas as this should really only affect the ranged, but if you do happen to get it, move away from everyone else for 6 seconds.
Any spec is theoretically viable for this fight, although Frost is currently struggling at the moment. It's probably best used only if your raid doesn't have an enhancement shaman for windfury. So, just like with Saurfang, for this fight you should simply dps your merry heart out. blow your cooldowns. Maximise dps; use indestructible potion before pull and haste when heroism is blown (if heroism is blown at pull, switch the order of your pots) DPS DKs should fare very well on this fight. In decent gear, you should be pulling at least 8k dps, and 10k dps in best in slot gear.