Shadowpriest Sezz'ziz

Pyramid
Clear the pyramid's base, climb to the Sandfury Executioner and take the Executioner's Key. Restore resources before opening the prisoner cages. Defend the stairhead beside the prisoners through the attacks ending with Nekrum and Sezz'ziz. Afterwards, finish the prisoners' dialogue to have Ukorz's gate demolished; wait for the gate to open before provoking Sergeant Bly.
Shadowpriest Sezz'ziz
Elite HumanoidSezz'ziz can undo the group's work on Nekrum with Heal and Renew while Psychic Scream disrupts the stairhead defense.
Abilities

Heal
Calls upon Holy magic to heal an ally.
Reserve an interrupt for Heal, including while damage is focused on Nekrum.

Renew
Dispel Renew from its enemy recipient so healing over time does not prolong the final wave.

Shadow Bolt
Hurls a bolt of dark magic at an enemy, inflicting Shadow damage.
Interrupt Shadow Bolt when the Heal interrupt is already covered.

Psychic Scream
Lets out a psychic scream, causing up to 5 nearby enemies to flee for 6 seconds.
Keep healers and ranged players away from Sezz'ziz's nearby fear. Use a fear-breaking ability if caught; Magic dispels do not remove this scream.
Tank- Keep Sezz'ziz on the cleared pyramid fighting ground rather than taking the group down into the remaining crowd. Recover control after Psychic Scream while the assigned interrupter continues stopping Heal.
Healer- Stand outside Sezz'ziz's nearby fear while retaining sight of the stairhead tank. Keep a feared tank in healing sight without following them into Sezz'ziz's fear range.
Damage- Keep Heal interrupted while Nekrum is the kill target, and remove Renew from whichever enemy receives it. Finish Sezz'ziz after Nekrum; ranged players should not move into Psychic Scream just to join the melee group.