Health:

• 10 Man:  8.645M
• 25 Man:  36.257M

Abilities:

• Slime Spray - Raining Green Ooze. Deals 5363 to 5637 Nature to enemies in cone. 1.5 sec cast / Channeled  -  Deals 6338 to 6662 Nature damage to enemies in a cone infront of the enemy. Instant 
• Ooze Flood - The Ooze Flood inflicts 5363 to 5637 damage every 1 sec and reduces move speed by 25% for 5 sec..
• Mutated Infection - The Mutated Infection inflicts 3900 to 4100 damage every 1 sec and reduces healing receieved by 50% for 12 sec.  After the Infection is removed a small ooze is created at the target's location. Instant 

Little Ooze:  Spawned each time Mutated Infection is debuffed / expired

• Sticky Ooze:  The Ooze sprays a puddle of Green Goo near the target. The Green Goo inflicts 2925 to 3075 damage every 1 sec and decreases move speed by 50%. 1 sec cast
• Weak Radiating Ooze - The Radiating Ooze inflicts 3413 to 3587 damage to enemies within 10 yards every 2 sec, it will also cause the Little Ooze to merge with other nearby Ooze.

Big Ooze:  Spawns with the first Sticky Ooze, a Sticky Ooze can merge with the Big Ooze and adds a stack of Unstable Ooze. Two Big Oozes can merge and combine their stacks. When the Ooze reaches 5 stacks it will explode.

• Unstable Ooze - Increases damage dealt by 20%. Instant
• Sticky Ooze - The Ooze sprays a puddle of Green Goo near the target. The Green Goo inflicts 2925 to 3075 damage every 1 sec and decreases move speed by 50%.  1 sec cast
• Unstable Ooze Explosion - Inflicts 9750 to 10250 damage to enemies within 6 yards. 4 sec cast
• Radiating Ooze - Inflicts 4388 to 4612 damage to enemies within 10 yards. Instant

The Fight:

First off, tank him in the center.   The raid should all stick close.

The room itself does Ooze Flood, which floods basically an entire quadrant of the room with slime.   Random order, but each one must occur at least once before re-randomizing (think Twin Valks abiltiies).  Use this knowledge to avoid the slimes when possible.   Also the precursor to the flood is pipes leaking out slime.    With most of the raid in the center and close, they should not have to to deal with this much, the center pattern area is safe.

Slime Spray is a random target directional cone cast.   It's a slow cast to watch for.   The raid merely has to scatter from the direction he's facing before the cast completes.    For less chaos, you may want to set up 2 clump groups behind Rotface.   Like one on the left, one on the right.   That gives him only 2 possible directions to look at, so left group move when he looks at you, right group moves when he looks at you.   Move back after the spray.

Mutated Infection is a Grobbulus type debuff, well a DoT and MS effect, but if cleansed or let it run its duration, it'll spawn a Small Ooze.   Those have to be dealt with in a specific manner which I'll explain below.   Just means don't insta-cleanse this until called for, if it's even neccessary.   Anyways, one further note on this is that it will occur faster as the fight goes on.   The speculative theory atm is that it's time based.    Longer the fight, the shorter duration, going down to even 15 seconds per Infection (12 sec debuff).   This would mean, Heroism and CDs should be popped early, kill fast as possible.

Small Ooze spawns when a Mutated Infection runs its course or is cleansed.   They will fixate (500K threat lead) on the person that was Infected.   They are not tauntable but they are snarable.   They have a damage aura so the Infected has to leave the raid to kite him out.    They also spit out slime puddles to avoid.    When 2 or more of them get close, they merge into a Big Ooze.    The goal of the Infected is to get them to merge asap.

Big Oozes are formed when 2 or more Small Oozes (or other Big Oozes) merge.  These guys are tauntable and can be tanked, but no longer snarable.    They also do the damage aura, and also gain 20% more damage (stacking buff) with each ooze they merge with.    You want to kite these, they will kill you.  

Now, you can either have an OT kite these around.    Or what we opted for is a Hunter Kiter.   Either way, keep threat, kite around the room around the slimes.    The Infected are to bring their small oozes to the kiter so they can merge them into the big ooze.

When the big ooze gets to 5 stacks of small ooze, it will stop and being to cast Big Ooze Explosion.   This is a multiple "Shadow Crash" thing.   It launches ooze rockets up in the air and explodes wherever you were standing when launched.    So if the entire raid is in the center, that's where all the ooze would be hitting.   Watch for the animation of the rockets to be launched, then gtfo from the center until they all exploded.

That's about it for the fight.   It just gets very hectic at the end as stuff spawns faster and faster.

Achievements:

Dances with Oozes - Defeat Rotface without exploding any oozes in 10/25-player mode.

• This sounds like it's either beat him fast enough so there wouldn't be enough Infections / Oozes to allow the Big Ooze to explode.    Or, being able to keep all the oozes away from each other / killing them fast enough so they can't combine.

Videos: