Professor Putricide: the first of the limited attempts bosses, and the first boss my guild didn't kill before new bosses were available (we got him the week after). Pleasingly complex, somewhat challenging in that plenty of things can kill your raid members, and a fairly tight enrage timer. Good stuff!
As usual, my focus here is not a guide for your guild to kill Putri, it's to do your job as DPS DK better.
To succeed against Putri Dish, you'll have to be good at avoiding the various potential killer abilities the Prof uses, switch targets quickly and effectively, and put out solid dps. As I mentioned a couple days ago, there's no reason for your first kill or two that you're not one of the last Orcs standing as the boss dies.
Pull/Phase One: We group in the middle to ensure that Putri drops the first two mutated slimes in the center. By the time the first two slimes are down, your army should be gnawing on Putri, and you should have your diseases up on him. As soon as your ap procs are stacked, release your hounds (DRW/ghoul/gargoyle). My guild tanks Putri where the volatile ooze spawns, which allows you to dps the boss hard, and kill oozes quickly. As soon as the volatile ooze spawns, if a blood rune is up, pestilence. If not, you can just get diseases up on the ooze manually. You should always have time to hit the ooze a couple times before the knockback, even if it chooses a melee.
On volatile oozes (green oozes), as you are chasing it to it's target, make sure that you're behind the ooze, lined up between the ooze and Putri. If the ooze reaches it's target and knocks you back, you'll get punted back to Putri, where you can start dps again! A nice little trick that saves running time. I usually Anti-Magic Shell when the green ooze is out, to help reduce the strain on my healers.
On gas cloud (orange oozes), we have ranged switch to it right away, while melee stays on boss until it picks a target. Obviously, you don't want to be next to it in case it picks you and blows up. I usually Icy Touch as I run to it, to save the gcd and get diseases up on it. When you're chasing the gas cloud, it's fairly likely that DBM will start yelling at you that malleable goo will be near you. Look for it, and run out the way if possible. If not, anti-magic shell or icebound fortitude to minimize the damage.
Putri always casts two choking gas vials, one behind him to his left, one to his right. If you're immediately behind him, if the tank is slow in moving him, you'll still remain unaffected by the hit debuff. This applies even more to the mass confusion of Phase Three.
If you aren't assigned to kill oozes and you get to stay on the boss: congratulations! You'd better do a ton of damage since that's all you have to worry about.
Phase Two: Unfortunately, we're not as lucky as the rogues and mage; we can't get out of Tear Gas. :( In Phase Two, I pop all my 'extra' abilities when I come out of tear gas and Putricide is running back from his table. Using Bone Shield and Horn of Winter at that point get me 'ready' for the next few minutes of dps. If you use gargoyle/ghoul/drw again as soon as it's off cooldown, you should get to use it one more time during P3 unless your group is very high dps (any fight that's more than 6 minutes long you should use gargoyle 3 times, or DRW 4 times). Otherwise, P2 is the same as P1.
Phase Three: As soon as I get hit by Tear Gas, my finger is over the Army of the Dead button (this will only be true for unholy DK); pop it right away, along with your other self-buffs. By the time Putri reaches your tank - we start him on the back wall and kite clockwise - you should be ready to beat Putri down. We heroism right here, so I also pop my speed potion, and as soon as gargoyle is up, it comes out to play too. Be very careful of choking gas, and if range/healers start dying, be ready for malleable goo to be cast on you - hit your defensive cooldowns if so. Eat face, but I don't recommend dining on dead Putri Dish; who knows what you might catch!
Even with running around so much, I usually do fairly well on this fight. I get beat out by a few casters, but I suppose my diseases ticking during Tear Gas helps on the meters. Just anticipate and switch quickly, and you'll do fine. This isn't a burn fight until the end, so don't expect to do too much more than 7k dps, and it's certainly possible to kill Putri with around 5k damage over the course of the fight. Just stay alive and dps until the very end!