What's up guys and welcome back finally to the Throne of Thunder raid guide. My name is Lore, and this video will cover the 25-man normal version of Primordius, the eighth boss in the instance.
So Primordius is another encounter with a whole lot of mechanics but a very simple strategy, the bulk of which involves dealing with the mutation mechanic. See the boss himself has a buff called Mutated Abomination that reduces the damage he takes by 75%. After the fight begins, several slimes called Living Fluids will spawn from the pools around the edges of the room and start to move towards him. Killing a Living Fluid will leave a puddle on the ground. This can be either a small, red puddle, or a larger purple puddle. Stepping in a red puddle will deal a small chunk of nature damage and also give you a buff that will increase either your mastery, haste, crit, or overall stats for 2 minutes. Those buffs stack. Once you've gotten a total of 5 stacks of helpful buffs, you'll gain another buff called Fully Mutated that lasts 2 minutes and allows you to ignore the boss's damage reduction effect. You'll also turn into a dinosaur.
So the DPS's job is mostly just killing slimes until they're fully mutated, and then focusing as much damage on the boss as possible before the fully mutated buff wears off. Ideally, melee should pick up their buffs first, with ranged focusing on killing Living Fluids until all of the melee are Fully Mutated. There's a couple things to note here though. First, once you're fully mutated, stepping in any more pools will give you a harmful mutation that lowers your stats instead, so try to avoid those if at all possible. Second, if someone is dispelled, it actually removes all of their positive and negative mutations and Fully Mutated. Generally speaking this means that if you do end up with a harmful mutation, it's best to wait out the rest of your Fully Mutated buff before asking for a dispel.
Now, there's way too many Living Fluids to kill them all, and you don't need to, so just focus on killing what you can to get your buffs rolling. Any extras that get through, or any of the red puddles that he steps on, will increase Primordius's mutation level. Eventually, he'll reach 100% mutation at which point he gains a buff that increases his damage by 10% per stack, and gains one of several random mutations, each of which give him a new ability.
So, Ventral Sacs causes him to deal a constant amount of raid damage. Gas Bladder will cause him to deal a very large amount of Nature damage split between everyone within 25 yards of him. Acidic Spines deals a chunk of nature damage to several random targets, which also splashes to others within 5 yards. Pathogen Glands will apply a heavy damage over time effect to several random players. Metabolic Boost increases his attack speed and causes him to use his other abilities more often; that includes any other mutations he might have, as well as a couple abilities he'll be using on the tanks, which I'll get into in a minute. Finally we have Erupting Pustules, which causes him to fire off several projectiles around the room.
Dealing with each of those abilities is largely in the hands of the healers -- there's going to be a lot of damage going out that you'll just have to heal through. However, everyone needs to be aware of Gas Bladder, Acidic Spines, and Erupting Pustules. When he has Gas Bladder, everyone should try to be within 25 yards to help split the damage. For Acidic Spines, ranged and healers should spread out to avoid causing extra splash damage. And for Erupting Pustules, just try to avoid getting hit. By themselves, none of his mutations are particularly annoying to deal with, but he can have up to 3 depending on how many Living Fluids are getting through. That turns into a lot of raid damage, and since there won't really be a great time to pop Bloodlust or Heroism otherwise since your DPS will all be juggling the Fully Mutated buff, I recommend using it then.
So, that just leaves the tanks. There's a few important things for tanks to keep track of. First off, he'll be using a frontal cone attack from time to time which does a heavy amount of Physical damage. Just don't point him at the raid and that should be fine. Second, he'll be stacking up a damage over time effect called Malformed Blood on his current target. That does mean you'll need to swap aggro, and 6 stacks seems to be about the sweet spot, but it also causes you to deal bonus damage to the Living Fluids as long as it's active, so whoever isn't currently tanking can help kill off oozes and even pick up their own Fully Mutated buff.
The most important thing for tanks to manage, though, are the purple pools. Remember, whenever you kill a Living Fluid, it can leave behind either a red or a purple pool. The red pools are good - those are the ones you step in to get the various buffs. The purple, or volatile pools, are very, very bad. First off, they will only ever give a harmful mutation if you step in them. More importantly, they'll slowly work their way across the room towards the boss. If they reach him, they'll instantly bring him up to 100% mutation and heal him for 10% of his health. So, tanks will need to be constantly moving Primordius around the edges of the room, kiting him away from the purple pools. You'll also want to be sure that your DPS never, ever finish off a Living Fluid that's close to the boss, on the off chance that it drops a volatile pool. Now, having him absorb one of these isn't necessarily a raid wipe, but it does make the encounter much, much more difficult than it needs to be, so avoid these as much as possible.
And that pretty much covers everything. The important thing about this fight is that, although there is a lot going on, it's really not very difficult overall. DPS kills living fluids and picks up buffs, healers keep the raid alive through the boss's mutations, tanks keep the boss away from the purple pools, and somewhere in the middle of all of that, the boss dies. That's pretty much it. If your raid can kill Durumu, Primordious should be no problem.