The 40 man version of Gluth was probably one of my favorite fights in the game. There was a lot going on and everyone was involved. It reminded me of a symphony were there are two different themes going on in two different parts of the room and every 105 seconds they would crash together for a new twist in the fight before settling back into the two distinct parts of the fight. Blizzard tried to keep the essence of the fight, but they have had a rough time of tuning this fight down to 10/25 people and it went through many revisions on the beta server. The end result is one of the more challenging fights in Naxxramas.
To start the fight the raid has to run through a big sewer pipe that does nature damage to everyone as they run through and then everyone takes fall damage as they jump out of the pipe into Gluth’s room. Most of the raid will be at 60% HP before the fight even begins. The tank needs to be the first person into the room and he runs the boss all the way to the far side of the room and gets rolling with the first theme of the fight.
The boss applies a Mortal Wound debuff to the tank that lasts for 15 seconds and reduces healing by 10% and stacks up to 10 times. That right there tells you that you will need two tanks for the fight. Gluth also does an aoe fear every 20 seconds which means he fears too often for a single tank to break every fear with berserker rage. Back in the day, Gluth was untauntable but bosses used to deaggro the tank if the tank was feared. So you would switch tanks by having the MT eat the fear while the OT broke it with berserker rage. While the MT was feared the Mortal Wound debuff would expire and then the OT would let himself be feared the next time while the MT broke the fear. It was the ultimate stance dance fight. But now, Blizzard wants all tanks to be able to tank all fights so you can’t assume the tank is a warrior that can break fears and since bosses don’t deaggro on fears anyway, Blizzard has simply made Gluth tauntable. It’s a reasonable solution to address the current tanking paradigm, but, in my opinion, it makes for a much less interesting, less elegant way to tank the fight. Gluth also has a frenzy/enrage that the hunters need to Tranquilizing Shot.
The second part of the fight is the hard part of the fight and it is going on in the back of the room, totally independent of the tank and boss. There are 3 grates on the floor in the back of the room where zombies spawn constantly throughout the fight. The zombies add a debuff every time the melee their target that increases damage taken by 100 and it stacks up to 99 times. Since there are a ton of zombies, that debuff would quickly stack up and overwhelm a tank if you tried to tank them. That means they must be kited. There are a lot of different strategies for which class can/should do the kiting, but, in my experience, a frost mage is usually the best. The mage needs to pick up the zombies as they spawn and keep them slowed with cone of cold, blizzard and frost novas (frost nova can be dangerous if you do it in the wrong place and snare a bunch of zombies next to a squishy). Hunters should be dropping frost traps and shaman should be dropping earthbind totems to help the mage. The zombies have a ton of HP which makes killing them a poor option, but since they aren’t going to be taking any damage, all the mage has to do is outpace healing agro in order to keep the kite going.
It is crucial that the kiting take place in the back of the room, as far as possible from the boss because if the zombies get anywhere near the boss, Gluth will turn and eat the zombie and every time he eats a zombie he heals himself for 5% of his HP. The fight has an enrage timer so if the kiting is sloppy and the boss heals too many times, you won’t kill him before the enrage.
Those are the two major themes of the fight, but there is one more mechanic that brings those two themes together. Every 105 seconds the boss uses an ability called Decimate which reduces the health of everyone in the room to 10% INCLUDING the zombies. Since Gluth just took 90% of the HP off of the zombies, they will all aggro to him and that means there is zero raid wide damage after the Decimate which means that all the healers should land a heal on the tanks to get them topped off. It may help to have a rotation for Nature’s Swiftness heals. Only after the tanks are topped off and stable do the healers need to start getting the rest of the raid topped off. When the Decimate happens, all of the dpsers need to switch to the zombies as they will all be heading toward Gluth and they will all be immune to snares. They will all be at 10% health which is still kind of a lot but if your dps switches quickly and hits hard, you will easily kill them all before they can heal the boss.
Once the zombies are cleaned up after the Decimate, the mages go back to kiting and everyone switches back to dpsing the boss. And you keep cycling through the phases until the big doggy is dead… or udead… again… whatever.