When you start the fight, Skylla will have 5 stacks of a buff called ‘Undying Loyalty’.
You won’t be able to kill the boss until all 5 stacks are removed.
The stacks are removed by destroying the pillars around the circle.
While the pillars are inactive, you should be DPSing Skylla to keep her health as low as possible.

• Fuel Nightmare Portal – A 13 second channel – Skylla targets a random pillar and tries to open a portal – Everyone must DPS the pillar down before the cast is over – Skylla will heal during the cast – Destroying the pillar will remove a stack of the bosses buff ‘Undying Loyalty’ – If the pillar is not destroyed in time then Skylla will gain a buff called ‘Nightmare Power Portal’, if Skylla reaches 5 stacks of this buff then you lose!

There are a few other mechanics to be aware of..

• All or Nothing – 5 second cast followed by a 5 second channel – At the end of the channel Skylla will hit all players, the more health she has the harder she will hit! – Keep Skylla’s health low, preferably at 1%, to avoid dying to this.
• Arresting Contagion – The boss gains a buff that lasts 7 seconds – This deals damage to anyone that moves! – The buff can be purged.
• Fractured Reality – 8 second channel – Red AoE to move out of, the AoE will either be an inner circle around the boss, or an outer circle around the edge of the area. – At 4 seconds into the cast the red will deal its damage and then switch to the opposite area. – Be sure not to be stood in the red!
• Infectious Bile – 4 second channel – Cast on a random player – The player will be mind controlled and spawn parasite adds – Another player will need to interrupt the cast to free their friend!