You're going to need at least two tanks to fight Rotface. One tank will be busy tanking Rotface himself, while the other tank will be busy kiting adds around the room. (We'll talk about where the adds come from in just a second.) There are only three different NPCs in this fight. The first is Rotface himself. The second mob is a Small Ooze. When you get two Little Oozes together, they turn into a Big Ooze. That Big Ooze is obviously the third mob.
When you pull Rotface, have your main tank drag him to roughly the center of the room. Your healers and DPS will be inside (or right up against) Rotface's hit box. Your second tank will be on the outside perimeter of the room, since that's where he or she will be tanking and kiting the Oozes. (I promise, I'll get to the adds in just a second.)
There are three gimmicks to the Rotface fight. The first are the ooze floods that cascade within the circle room. The second gimmick is Rotface's periodic Slime Spray. The third are those Little and Big Oozes we were just talking about. You'll have to handle all three of these issues while consistently applying a steady stream of DPS to Rotface.
The Ooze Floods come from the pipes surrounding the perimeter of Rotface's room. The ooze floods themselves hit the corners of the room (northwest, southwest, northeast, and southeast). The floods are sizeable, but they'll never completely reach the center of the room. The healers and DPS won't have to worry much about the floods, except for the rare occasion when they need to run to the outside perimeter. The Ooze Flood deals damage to anyone in the flood, as well as slowing their movement speed. Consider this the fire you don't want to stand in.
The second trick is the Slime Spray. This is a relatively easy thing to handle, and I'm pretty sure it's just there so that the healers and DPS don't fall asleep. It's obvious when Rotface is about to spew a Slime Spray. The power has a second and a half cast time, so any method you use to view a target's cast bar will reveal the upcoming Slime Spray. Once the cast bar finishes, the Slime Spray will spew for about five seconds in a cone toward its target. Just don't stand in it. The Slime Spray targets a random raid member with each cast, so you'll need to be fairly attentive.
The last trick is the Little Oozes and Big Oozes. They don't just simply appear. Rotface drops a debuff on a random raid member called Mutated Infection. This infection is a killer DoT, which will quickly kill anyone if they're not rapidly healed. However, you can't simply cleanse Mutated Infection -- as soon as you do so, a Small Ooze appears. This Small Ooze is not tauntable, but it doesn't hit very hard. When two Small Oozes get near one another, they will merge and become a Big Ooze. Big Oozes will continue to absorbs Small Oozes, gaining a stack of Unstable Ooze.
Unlike the little counterparts, Big Oozes do hit hard. This is why you have to kite the oozes to the outside perimeter, where the second tank can pick up the growing Big Ooze. You can't just leave everyone with their own personal Small Ooze by Rotface, or they'll merge and wreck shop on the entire raid. Both Little and Big Oozes spit slime on the floor similar to Rotface, and radiate damage to anyone around them.
When the Big Ooze absorbs enough Small Oozes so that they have 5 stacks of Unstable Ooze, they'll explode. The explosion spews dangerous slime to the center of the room, so your raid should spread out when the Big Ooze is about to blow up.
So, here's the general run down of the fight. Have your main tank pull Rotface to the center of the room. The second tank hangs out in the outside of the room. When Rotface puts Mutated Infection on a raid member, that raid member should go to the outside of the room near the second tank. When the infected raid member is in position, that's when they should be cleansed. The Small Ooze will spawn, and the raid member kites that Small Ooze around. When the second Small Ooze spawns, combine the two and have the second tank grab it. Kite the Big Ooze around the outside of the room, being careful to avoid slime pools. Each additional Small Ooze should be kited to the Big Ooze, and the entire raid should spread out when the Big Ooze is about to explode. Rinse and repeat until Rotface is dead.
The biggest challenge with this fight will be realizing you have a Small Ooze, and getting it out to the Big Ooze. Since you have to do this kiting while dodging all the slime on the floor, it can be challenging for folks who aren't used to kiting mobs.
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