

Players have to deal with Swelling Corruptions spawned during the boss phase.
A pool is spawned under the boss during the Split phase that will slowly grow. The puddles have to be dealt with faster to handle this new mechanic.
Immerseus is a two-phase fight, which alternates until the boss reaches 0 Corruption and dies.
When Immerseus reaches 0 health, he bursts into a shower of puddles that will slowly try to gather in the middle.
Kill Sha Puddles and heal Contaminated Puddles before they reach Immerseus to lower his Corruption by 1.
EVERYONE
SOAK
On Heroic, Immerseus spawns a slowly growing Pool that deals small Shadow damage every 1 second to those inside it.
This Pool expands whenever a Puddle reaches it and shrinks when a player walks into it.
Players should alternate using defensive cooldowns to shrink the puddle by walking into it.
During this phase, one Sha Puddle is formed for every 4 Corruption Immerseus has.
Destroying the Puddle before it reaches the boss removes 1 Corruption.
Sha Residue is a stacking debuff applied to all players within 10 yards of a dying Sha Puddle, increasing their damage done to Sha Puddles by 25% for 10 seconds.
During this phase, one Contaminated Puddle is formed for every 4 Corruption Immerseus has.
Healing a Puddle to full before it reaches the boss removes 1 Corruption.
Congealing causes the Puddle's speed to decrease the higher its health is.
Upon reaching full health, the Puddle will release Purified Residue, giving any players within 12 yards to gain 25% mana and a 10-second stacking 75% healing buff.
During this phase, one Sha Puddle is formed for every 4 Corruption Immerseus has.
Destroying the Puddle before it reaches the boss removes 1 Corruption.
Sha Residue is a stacking debuff applied to all players within 10 yards of a dying Sha Puddle, increasing their damage done to Sha Puddles by 25% for 10 seconds.
During this phase, one Contaminated Puddle is formed for every 4 Corruption Immerseus has.
Healing a Puddle to full before it reaches the boss removes 1 Corruption.
Congealing causes the Puddle's speed to decrease the higher its health is.
Upon reaching full health, the Puddle will release Purified Residue, giving any players within 12 yards to gain 25% mana and a 10-second stacking 75% healing buff.
Immerseus starts the fight with 100 Corruption.
Every time he is reduced to zero health, he splits into many adds that need to be dealt with.
This repeats until he reaches 0 Corruption.
EVERYONE
SPREAD
Every 10 seconds, Sha Bolt deals small Shadow damage to every member in the raid and splashes to all within 5 yards, leaving a puddle on the floor almost instantly.
This splashes to targets within 5 yards. This pool, Sha Splash, deals moderate Shadow damage.
EVERYONE
DON'T GET HIT
TANKS
TANK SWAP
Each boss phase, Immerseus will gain a buff that has a stack for every 2 corruption he has.
The buffs' stacks will be lowered for each hit he receives, almost certainly removing the buff within a few seconds.
Upon removing the stack from the boss, the player will gain the stack as a debuff.
When this debuff either ends after 6 seconds or is removed, a Congealed Sha is spawned. These should be grouped and AoE'd down.
If a player walks inside the boss, they will be knocked back and dealt Shadow damage.
Melee players should utilise the large hitbox to avoid going near the barrier.
Each boss phase, Immerseus will gain a buff that has a stack for every 2 corruption he has.
The buffs' stacks will be lowered for each hit he receives, almost certainly removing the buff within a few seconds.
Upon removing the stack from the boss, the player will gain the stack as a debuff.
When this debuff either ends after 6 seconds or is removed, a Congealed Sha is spawned. These should be grouped and AoE'd down.