Immol'thar

West: demon prison
Finish the remaining pylon guardian packs before approaching Immol'thar. Clear the prison before starting an optional warlock ritual there; Lord Hel'nurath belongs to that summon, not an ordinary West clear. Groups without a ritual continue to the library after Immol'thar.
Immol'thar
Elite DemonImmol'thar divides attention between the tank's Infected Bite, summoned eyes and a portal that can separate a player from the fight.
Abilities

Eye of Immol'thar
Assign ranged damage to destroy the summoned eyes before returning to Immol'thar, keeping the tank on the boss.

Portal of Immol'thar
Track the player moved by Portal of Immol'thar. If it takes the tank away, pause damage until the tank is back in control.

Infected Bite
Inflicts Nature damage to an enemy every 10 sec. and increases the Physical damage it takes for 3 minutes.
Remove Infected Bite as a disease; it causes repeated Nature damage and increases the victim's incoming Physical damage.

Trample
Keep the healer and assigned eye killer outside Trample's nearby melee damage.

Enrage
Keep a defensive response available for Enrage, especially if Infected Bite remains on the tank.
Tank- Hold Immol'thar on cleared prison ground while the assigned ranged player handles the eyes. Re-establish control after a portal displacement before the group resumes full damage.
Healer- Remove Infected Bite and watch the portal target as well as the tank. Keep ranged healing space outside Trample, and prepare for Enrage if the disease has not been removed.
Damage- Keep the assigned eye killer on new summons instead of making the tank chase them. Pause when the tank is moved by the portal and resume once Immol'thar is controlled again.