Professor Putricide is the last boss of of ICC's Plagueworks. At its core, it's not an insanely complicated fight. Certainly not on the magnitude of the Blood Prince Council or Valithria Dreamwalker. The trade-off for that is that the execution is very, very tight. There's not a lot of room for error here.
Like the Rotface fight, the two tanks in this encounter have very distinct roles and a lot of pressure is on the tank not holding the boss to do their job well. It's very easy for that tank to wipe the encounter if they don't keep up.
Professor Putricide is a 3-phase fight. The first two phases are very similar and will see each tank performing their same tasks throughout. One tank will be the Putricide tank and the other will be the Abomb driver.
Once you've decided which tank is going to perform which role, everyone needs to get in position. The Putricide tank (and the rest of the raid) will start on the side of the room with the orange vat. Pull the prof and drag him back near the wall under the vat. Soon after the encounter starts (and on regular intervals thereafter) he's going to spawn 2 slime puddles under the feet of two of your raid members. You'll want to move so that you're tanking the Prof near these puddles. Specifically near the puddle that the Abom driver is soaking up (more on that in a moment).
Not long after that he's going to cast Unstable Experiment and summon a green ooze from the vat on the other side of the room. The ooze will target a random raid member (other than the tank) and link with them, causing immobilization and heavy damage, and then start moving towards them. The link is very visible. It's very green and arcs through the air across the raid. When/if the ooze reaches the linked individual it will explode, sharing it's damage among all targets in the immediate area. Don't do anything special here. Since you're already taking damage from the prof, you don't want to stack on the linked person (as the rest of your raid should be). Just wait for your raid to kill it. Once it's dead, move the Prof to the center of the room. (The raid should follow.) If/when there's ooze puddles in the area, tank him next to them just like before.
The second time the Prof casts Unstable Experiment, he summons an orange ooze from the orange vat. Again, it's going to link with one of your raid members. Unlike the green one, they'll be able to move and will have to kite this one while the raid burns it down. You just keep doing your thing. Once it's dead, move back under the orange vat and get ready for another green ooze. This process will repeat continually.
Your positioning may be a little unclear from all that, so let me try and summarize really quick. First priority is being in the correct area of the room: under the orange vat for the green ooze summons and in the middle of the room for the orange ooze summons. Second priority is tanking him near any slime puddles that are in the general vicinity of where you should be.
Edit (6/7/10), Alternate Strat: Our guild has been using a different positioning strategy lately and it's worked very well for us. Tank Putricide near the doors where you enter the room. Only move him to keep your raiders away from bad stuff. Your raiders should still switch sides of the room, depending on which ooze it going to spawn, but it severely cuts down on their movement. As long as they stay on the opposite side of the center line as the spawning ooze, everything should be peachy.
Abom tank (driver):
You can start the encounter anywhere, though I like to line up on the opposite side of the room as the rest of the raid, near the orange vat. As soon as the Prof tank pulls, run up to the table where the Prof was standing and start drinking from the flasks there. I usually go kitty and Dash to get me there a little faster. It takes about 5 seconds to drink the potion once you click and you don't get a channeling bar (though you do get a drinking debuff). Once the drinking is done you turn into a large abom, not very dissimilar from Rotface and Festergut.
A quick note here, the transformation is a disease. You do not want this to be cleansed! If you have priests, shamans, or paladins in your raid, make sure they are very aware of this fact.
The other thing to note is that the Abom puts out a raid-wide aura that ticks AoE damage. It's not extreme, but it's there. So if you see floating damage numbers popping up all over the place, this is why.
You now play a key role in this encounter and your ability to perform it well is about 90% of the determining factor of your raid's success or failure. No pressure.
When you're driving the Abom, you have 3 abilities, each very important and used very specifically.
Your first priority at almost any given time is to soak up the slime puddles that the Prof spawns under your raiders. You do this by standing in the ooze puddle and spamming your "1" ability, Eat Ooze. The puddles will gradually shrink until they disappear. This has the added bonus of filling your resource bar. You can attack while soaking up the puddles, so if there's any oozes or Professors in melee range as you're soaking, you should be whacking away at them. This is why you want the Prof tank holding him near the ooze puddles.
What's key here is that the ooze puddles will slowly expand the longer they're out. If you're not on top of soaking them up you can reach a point where you fall too far behind and cannot catch back up as more puddles spawn. This will ultimately wipe your raid.
The only time that soaking up a puddle is not your top priority is when either the green or orange oozes spawn. Shortly after they fully form, you need to get in range of your "2" ability, Regurgitate Ooze. This slows the speed of the ooze significantly and puts a DoT on it. This is key in helping your dps get these things down quickly and, more importantly, keeping them from getting to their intended targets.
Note that this uses 45 of your accumulated ooze energy, so you don't want to go flinging your ooze around willy-nilly. Be conservative so that you have it available every time an ooze spawns. Missing one could very easily wipe your raid.
The last ability on your bar, in the "3" spot, is Mutated Slash. Any time you're soaking up puddles and something bad is in melee range, you should be nailing him with this as well. If there's no puddles out, but there is an ooze, you should be chasing it while spamming this ability after you've slowed it with your nasty gut juices. The moment you see puddles form, peel off and get to soaking them.
Phase 1 ends when your raid gets the Prof to 80%. At that point he stuns everyone in the room and runs to his table to prep for phase 2.
Edit (9/13/10): Now with video!
As far as the tanks are concerned, nothing really changes here. All the abilities from Phase 1 will still be in play.
Additionally, the Prof will start tossing out bouncing goo balls at random raid members. Anyone in their path should GTFO. He also starts dropping glowing orange beakers of doom that will explode after 20 seconds. Everyone should watch out for these and avoid them.
Phase 2 ends when the Prof drops to 35%. Again, everyone gets stunned as the phases shift.
As you get the Prof close to the end of Phase 2, it's important to time your DPS so that the phase ends while there's no green or orange oozes forming or active. Keep an eye on his health bar and plan accordingly.
This is a burn phase. It's a flat-out DPS race before massive damage is able to wipe your raid. At the start of this phase the abom tank is automatically cleansed, becoming his normal tanky self. This is why it's important there's no oozes out at the start of this phase...you'll have no way to slow or debuff them while your raid tries to get them down. Additionally, you need all your DPS on Putricide the moment the phase starts. Wasting time on the ooze will almost certainly lead to a wipe.
At this point the tanks need to start kiting the boss around the edge of the room. The rest of the raid needs to stay either behind the boss or to the inside of the room. Putricide will still be spawning ooze puddles under people's feet and it's important that the kite path be kept clear. The puddles will slowly expand, eventually taking over the room if Putricide isn't killed quickly enough.
During this phase he hits pretty hard. Additionally he'll be stacking a debuff on the tanks. The higher the debuff stacks, the more damage that's done every 3 seconds when it ticks. The damage is applied to the whole raid, not just the infected tank. On top of that, the damage done as the stacks are applied is increased exponentially. 1-2 stacks is pretty manageable. 3-5 is pretty bad. More than that is wipe-inducing.
If the disease drops off (most likely because the tank died), Putricide is healed for 300K per stack that was on that tank. So it's imperative that you do what you can to help the healers keep you alive. Rotate through your cooldowns responsibly while you have aggro.
Ideally the tanks should be taunting back and forth every 2 applications of the debuff.
And that's the fight.
On 10-man you're looking forward (and I mean really looking forward) to the Unidentifiable Organ. It's the only thing from 10-man you'll want, but...wow. Amazing.
From 25-man you can hope for Astrylian's Sutured Cinch, which is a pretty good belt for ya. There's also the Vanquisher's Mark of Sanctification which you can use to upgrade one of your tier pieces.
As with all my boss strats, I'm writing from the overall perspective of a Bear tank and what they will need to do. For you Cats reading this blog, I suggest you check out Dinaer's guides on Forever a Noob. They're written for Rogues but are a pretty good guide for melee in general and his gear drop suggestions (with the exception of weapons) will be spot on for Cats. If I have additional insight, I will try to add it in my blog.