***Reminder that these are based off of PTR 10-man testing info and all information regarding boss health, dmg output, debuffs, percentages, etc are subject to change when they go live!***

Primordius is the 8th encounter in the raid.

He as ~349mil health (10-man).

This fight will require

1. 2 Tanks
2. 3 Heals
3. 5 DPS

This fight has some Yor'sahj characteristics to it, in the sense that the he has a pool of abilities, and only selects random ones throughout the fight as he "evolves".  Unlike Yor'sahj and being able to control those by killing appropriate slimes, you cannot control which "Mutation" abilities this boss will gain.

The overall main mechanic to the fight is the Evolution/Mutate mechanic.  This will affect both the boss AND the raid.  First I will list his abilties and how his evolution mechanic/abilties work.  Then I will list how it affects the raiders.

The bosses abilities are as follows

1. Primordial Strike - He claws at his current target, dealing ~650-750k physical damage to all players in a 7-yard cone in front of him.
2. Malformed Blood - Tank debuff/buff ability.  Deals 10k nature damage every 3 seconds, and causes the afflicted player's attack to "Congeal Blood".  This ability stacks, forces tank swap.  Lasts 1 minute.
   
   • Congeal Blood - Deals 20k additional nature damage to "Living Fluids" and "Viscous Horrors"(Heroic Only) adds.
3. Evolution - Primordius' main mechanic.  He has a energy/rage style bar that slowly builds over time.  When it reaches 60 he will "Evolve".  In addition when Living Fluids and Mutagenic Pools touch him, he will gain an additional ~3 energy/rage, causing him to evolve faster.  Evolution increases all damage he deals by 10% per stack and will grant him a new "Mutation" ability.  He will start the encounter with a full 60 energy/rage, so he will have 1 ability to start with, then gain up to a max of 3 (4 in heroic). Once he has 3 mutated abilities and evolves further, he will lose an ability and gain a different.
   
   • Ventral Sacs - Sacs located around Primordius' frill will periodically erupt, dealing 20k nature damage to all players every 1 sec.
   • Gas Bladder  - Allows Primordius to spray "Caustic Gas", dealing 4.05mil damage, split amongst all players within an 18 yard cone
   • Acidic Spines - Fires Acidic Spines every 5 sec, inflicting 150k nature damage to all players within 5 yards of the target.  Spread out 5 yards.
   • Pathogen Glands - Sprays a Volatile Pathogen at a player, inflicting 60k nature damage to a player every 1 second and summons a "Living Fluid" add.  You can see who is affected by this via a red beam channeled on them for the duration of the effect.  Player will need to run away from the boss to allow more time to kill adds that spawn during this ability so he doesnt evolve faster.
   • Metabolic Boost - Allows Primordius to use his abilities more often and increases his attack speed by 50%
   • Erupting Pustules - Pustules erupt every 5 sec, showers the area with corrosive blood that deals 275-325k nature damage to anyone within 2.5 yards of the impact.

Around his room are pools of blood/liquid.  These will spawn 2 types of adds, "Living Fluid" and "Viscious Horror"(Heroic only).  I am not 100% certain whether these adds will spawn through the whole fight, if it is time based, or if there are only so many adds that spawn.  Most vids I have seen, don't last long enough to tell because people are stupid and die.  One video showed adds completely stopped spawning after 2 1/2 minutes, another one where a grp of 6 people actually killed him had adds spawn the entire fight, but it was only a 3 min 20 sec fight.  And they exploited a mage bug on him.

1. Living Fluid - These adds will have 394k health.  They should only spawn during the initial "Phase" of the encounter and after that, only when Primordius' uses his "Pathogen Glands" ability. Again, that is uncertain.
   • Mutagenic Pool - When the adds are dies, it leaves behind a Mutagenic Pool that can be absorbed by Primordius OR players to give them their "mutation buffs".  There are 2 types of these "Mutagenic Pools" that are not mentioned in the tooltips/wowhead dungeon journal.
     1. Normal pools will spawn, they will be smaller red pools that remain stationary.
     2. Violent pools will spawn, these will be red and supposedly have a slight purple tint to them. They will be more... "active" looking, and will slowly move themselves towards the boss.  They also supposedly deal more damage than the normal pools, so it was recommended that tanks/healers pick them up, but I never saw a drastic difference in vids and saw pretty much anybody just picking up the pools.
   • Mutate Primordius - See above in Primordius' "Evolve" Section.  When pools or adds reach him etc.
   • Mutate Player - When a player steps in a Pool, they will absorb it, receiving 185-215k nature damage and causing a "mutation".  This is where it gets kind of tricky.  The mutations will affect you in 4 different aspects, both positively AND negatively.  You should always be getting the "positive" buff first, BUT for each stack you get of a specific "positive" buff, you have get an increasing 10% chance to receive the "negative" buff effect.  The aspects these "mutations" affect are  "All Stats", "Mastery", "Haste" and "Critical Strike".  **IMPORTANT NOTE: If you dispell a player who has mutations, they lose ALL buffs AND debuffs gained from mutation effects**. These mutations last 2 minutes each. So if you lose all your stacks of crit, and have like 3 bad stacks of crit, youll want to dispel, etc.
     
     • Helpful Mutation: Thick Bones - Increase all stats by 10%.  Can stack up to 10 times.
     • Harmful Mutation: Fragile Bones - Decrease all stats by 10%.  Can stack up to 10 times.
     • Helpful Mutation: Clear Mind - Increase Mastery by 10%.  Can stack up to 10 times.
     • Harmful Mutation: Clouded Mind - Decrease Master by 10%.  Can stack up to 10 times.
     • Helpful Mutation: Improved Synapses - Increase Haste by 10%.  Can stack up to 10 times.
     • Harmful Mutation: Dulled Synapses - Decrease Haste by 10%.  Can stack up to 10 times.
     • Helpful Mutation: Keen Eyesight - Increase Crit Strike by 10%.  Can stack up to 10 times.
     • Harmful Mutation: Impaired Eyesight - Decrease Crit Strike by 10%.  Can stack up to 10 times.
2. Viscous Horror (Heroic Only) - A heavily mutated add
   • Black Blood - Spreads its mutated blood to current target, dealing 20k nature damage every 3 sec.  Coats the player in "Black Blood".  Lasts 1 minute and stacks.
     • Black Blood - When player is affected, deals 20k additional nature damage to the boss.
   • Deadly Mutagen (wipe mecahnic)- If a Viscous Horror gets close to Primordius, he will explode, dealind 925k-1.08mil damage to the raid.

One aspect of the fight that I have seen mentioned, but cannot find tooltips regarding is a "Transformation" mechanic.

• Apparently, Primordius only receives 50% of actual damage dealt by non-transformed players.  In order to bypass this, players need to "Transform" into Sauroks.  They can do this by receiving an overall 10 stacks of "Mutations" from picking up the pools after killing "Living Fluids".

It appears this fight is a race.  The goal should be to pull the boss to the middle of the room, allowing equal time for all adds to reach the boss.  Most vids Ive seen have the boss tanked by a wall between pools.  Seems ineffective to me, but that may be due to counteracting the "Gas Bladder" mutation on the boss.  You will want to kill adds quickly and have raiders gain as many mutations and stacks as possible, while being respectful of the damage it will deal to you by picking up the mutations.  The type of mutation you will receive is random, and like I said, you should always be getting the "helpful mutations" first, but the more stacks you get of a mutation, the greater chance you will start getting stacks of the "harmful" mutation, negating the "helpful" stacks.  Once you get 10 overall mutation stacks to be transformed into a Saurok and hopefully a good amount of stacks of the stat you want, just nuke down the boss while hopefully still being able to control adds so he doesnt evolve too quickly. And if the "helpful mutations" start falling off due to time, dispell to remove bad effects and try to get stacks back up if there are any pools available.

This video is the one I mentioned where the adds stopped spawning.  It was about 2:15 into the pull (2:30 in the vid) that the last add spawned, and the fight was 6+ mins.  They ended up not getting the kill.  But this is the longest video I found, so I tend to think the adds stop spawning at a later point.  However, there are some 3-3:30 min vids where adds are spawning non-stop.  So not sure which aspect of it to go with.  But this vid shows the best way to handle the fight overall it seems.