Kirtonos

Reliquary and porch
Clear the entrance classrooms and the Chamber of Summoning on the way to the porch. If the group has Blood of Innocents, gather inside before using Kirtonos's brazier. Fight against solid stone rather than the open windows, where Wing Flap can throw a player out of the instance.
Kirtonos
Kirtonos the HeraldElite UndeadKirtonos tests whether the group can keep a frontal stun and knockback away from the porch windows while recovering from curses and mind control.
Abilities

Wing Flap
Strikes enemies in a cone in front of the caster, knocking them back.
Put solid stone behind the tank and keep everyone else out of Kirtonos's front; Wing Flap can throw a player through a window.

Swoop
Swoop damages and stuns enemies in front. Attack from the flank or rear rather than sharing the tank's position.

Curse of Tongues
Forces nearby enemies to speak in Demonic, reducing their casting speed by 50% for 15 seconds. Only one curse per warlock can be active on any one target.
Remove Curse of Tongues from the healer first when its casting penalty threatens healing, then from other casters.

Dominate Mind
Use crowd control on a dominated teammate without killing them, and resume the boss fight when control ends or is removed.

Disarm
Disarms an enemy, forcing it to stop wielding its weapon for 10 seconds.
Weapon attackers lose their weapon during Disarm. Avoid committing a weapon-dependent burst into that debuff.

Pierce Armor
Reduces an enemy's armor by 50% for 20 seconds.
Pierce Armor weakens the target's protection against melee damage. Use mitigation and prioritize healing that target while the armor penalty is active.

Shadow Bolt Volley
Hurls missiles of dark magic, inflicting Shadow damage to nearby enemies.
Expect Shadow damage beyond the tank from Shadow Bolt Volley; do not let the porch positioning put the rest of the group out of healing reach.
Tank- Fight with solid stone behind you and Kirtonos's frontal cone away from the group. Use mitigation when Pierce Armor makes his melee hits more dangerous.
Healer- Stand to the side of Swoop and Wing Flap, within reach of the tank's wall position. Call for Curse of Tongues removal before its casting penalty combines with Pierce Armor or a volley.
Damage- Stay outside the frontal cone, control a dominated teammate without killing them, and help remove Curse of Tongues if your class can. Save weapon-dependent burst until Disarm ends.