Festergut is probably the easiest of the three bosses in the newly opened Plagueworks of Icecrown Citadel.  He is a creation of Professor Putricide along with his twin, Rotface.    This encounter is a pretty big jump in difficulty compared to the first four bosses in the Lower Spire, however, unlike his twin which requires a lot more movement and coordination, this fight is mostly a gear check.  The mechanics aren’t too complicated.  Most of your raid will do nothing but straight dps or heals the entire time.  However the fight does require some movement and will put a lot of pressure on your healers to keep everyone alive.

Gear Requirement

He's so purdy!

Your raid is going to need some very nice gear to be able to down Festergut.  There is a lot of damage going out, to both the tanks and the raid, as well as a fairly unforgiving enrage timer.  Ideally you’ll have farmed quite a few pieces from the first four bosses of Lower Spire.  If your raid hasn’t stepped foot in Icecrown Citadel before, you’ll likely have a very difficult time downing Festergut.

Group Make-up

Festergut requires the use of two tanks and you’ll definitely want three healers the first few times you go in.  An equal division of ranged and melee dps is ideal so that its less likely you’ll need to have people moving between the two groups.  Tank damage is going to be very high during some phases of the fight, so you’ll want to bring someone to help with tank healing - preferably a Discipline Priest.  However, raid damage is going to be high in some phases as well, so make sure your healers are strong at both.  My group went with a Holy Paladin, Discipline Priest and Resto Shaman.

The Pull

Have your weaker tank pick up the boss first.  The tank isn’t going to take a ton of damage at first.  However, don’t grow lax because of this.  The tank can still die easily if he doesn’t get heals.  Make sure you aren’t surprised and he dies right at the pull (hit him with a Holy Shock as you run into position).  At the start, most of the damage you’ll be healing is going to be raid damage.  Everyone in the raid will be taking quite a bit of unavoidable damage as the room fills with Gaseous Blight that will need to be healed through.  Putting Beacon of Light on your tank and healing the raid is a great idea for the entire fight, since only one tank will be taking damage at a time.  Judgement of Light will also do a ton of healing here to help with the AoE damage.

Its best to work out beforehand where each of your ranged dps and healers are going to stand.  Ideally, you’ll want the Holy Paladin (or your strongest tank healer) standing right in the center, just a few steps forward where you come into the room.  The two other healers will be on either side of you about 10 yards away, and the other ranged dps will spread out about 10 yards beyond the other healers.  With this setup, you (as the Holy Paladin) won’t have to worry about anything during the fight except healing your butt off.  This is ideal because of the trouble we can have while trying to move and heal at the same time.  Putting the other healers right next to you means that none of the healers will have to move too much.

Like always, if you’re going to use Army of the Dead off the pull, make sure the death knight stands back far enough so that one of the ghouls doesn’t pull the boss himself.

Update:  It seems that the best positioning is to always have 3 to 4 people at range (preferably 4 to be safe).  You can move any additional healers or dps up into melee range that way they never have to worry about Vile Gas or moving for spores.

Festergut Positioning

Dealing with Vile Gas

Vile Gas is the reason your ranged dps and healers can’t just stay stacked together the entire fight.  When one of your raid members gets Vile Gas, they’ll lose control of their character for about 2 seconds and deal AoE damage to everyone around them (as they vomit uncontrollably).  The damage to a single person isn’t terribly high and staying spread out makes this ability fairly easy to ignore.  The ability can not be cast on your melee dps or tanks so they don’t need to spread out.

The big threat of Vile Gas is when one of your healers gets hit by it at a key moment, rendering them useless for a couple seconds, unable to heal, and possibly causing deaths.  Every Man For Himself can help out a ton with this if you are a human.  If things are getting crazy and you absolutely need to heal (which is very possible), don’t be afraid to pop Every Man or Divine Shield in order to get back into the action quickly.  Two seconds without heals can be a lifetime in this fight.  Otherwise, if everyone is topped off and your other healers seem to be handling things well, let the timer run out on it and save your cooldowns for if you get hit with it again.

Gas Spore

The first major ability your raid is going to need to worry about is Gas Spore.  Two of your members at random will be afflicted with the spore.  Its possible that two melee or two ranged will be afflicted, but if your raid is distributed evenly it will usually end up being one of each.  Your melee dps won’t have to worry about this ability much unless two of them get hit with it.  At every cast, your ranged dps should collapse onto the center healer (blue dot in the diagram).  Your ranged dps should be on the outside so that your healers don’t have to run as far and can get back to healing.  The center healer shouldn’t have to worry about the spore at all.  If two melee dps get the spore, one will have to be called out quickly to move to the ranged position until the spore explodes.  Similiarly, if two ranged get the spore, one will have to move in to melee range (ideally one of the ranged dps).  As soon as the spore explodes, everyone moves back to their original position.  Then rinse and repeat.  This is the only movement your raid needs to do during this fight.  Ideally, only 4 or 5 people will need to move with each spore cast and the rest can concentrate on just doing their job.

Gastric Bloat and Inhale Blight

You’ll need to be aware of both of these abilities for different reasons.  Gastric Bloat is a debuff that gets cast on your tank that stacks up to 10.  It stacks once about every 10 seconds, and with each stack, your tank will be doing more damage (ie, producing more threat).  The important thing for you though is that if it reaches 10 stacks, it will explode, causing massive damage to your raid and likely causing a wipe.  Therefore, your tanks need to switch before it reaches 10 stacks.  Since the tanks are taking a ton of damage, make sure you are ready to heal the new tank before the switch.  Ask them to give you a warning a couple seconds before the taunt so you can get Sacred Shield, Beacon and your heals on the new tank.

Inhale Blight is an ability that increases damage done to the tank by quite a lot.  The good news is that with each cast, the AoE damage your raid is taking gets reduced significantly, meaning your raid healers can help you out a lot more with tank healing.  Festergut will cast Inhale Blight 3 times total before it resets.  After he has inhaled 3 times, your raid will be taking almost no AoE damage, but your tank will be getting hammered and will be very difficult to heal.  Your tank will be very difficult to keep up with 3 stacks of Inhale Blight on him, so make sure to spam hard and use your cooldowns as necessary (bubble + Hand of Sacrifice can help, for example).

Pungent Blight

The last ability you need to worry about as a healer is Pungent Blight.  After Inhale Blight reaches 3 stacks, Festergut will release the gas within him, causing AoE damage to everyone in the room.  At the same time, the gas itself will continue to do AoE damage to everyone, the same as it did at the start of the fight.  You’ll need to be very quick with your heals to keep everyone alive (Flash and Holy Shock everyone who gets low).  The good news is, your tank damage should be back down to a more manageable level, so your raid healers can go back to raid healing.  Just before Pungent Blight is a great time to use Heroism to help your healers out (or possibly even earlier to help with tank healing after the 3rd inhale).  You should also ask your raid to use any Healthstones or Potions they have at this time.  If you’ve made it this far, you’re good, the rest of the fight is just a repeat.  Keep up your mana and you’ll be done in no time.

Summary

Here are the main points to keep in mind:

• Let your other ranged/healers run to you in the center during Gas Spore so you can focus on healing
• Raid heal at the start with Beacon on the tank (FoL, HS, HL on the melee)
• Gradually increase your healing on the tank as Inhale Blight and Gastric Bloat stack (switch to more Holy Light use)
• Bubble or Trinket out of Vile Gas if you have to
• Be ready for tank switches and for Pungent Blight
• Heal like mad

Good luck!

Loot to watch for

• Festergut’s Gaseous Gloves
• Signet of Putrefecation