Boss Focus: Terestian Illhoof
In a Nutshell
Terestian Illhoof is an optional boss that only controls a very small amount of trash respawn inside Karazhan. He resides inside the library near the Shade of Aran. You will find him in a room that is hidden behind a suspicious bookshelf inside a room that is filled with Shadow Pillagers and Homunculi.
Illhoof himself is a very add-lasting encounter without phases, however there are a few twists that define the course of the battle. The key to the fight is to control the swarming adds and to reduce uptime of the Demon Chains to a minimum.
Rundown
The encounter, more or less, requires you to bring 2 tanks. Your main tank should tank Illhoof somewhere near the green runic circle in the room and your off tank will take care of Illhoof’s personal Imp, Kil’rek.
Your main tank will be taking solid damage. Nothing too spiky, but he needs attention. Your off tank won’t be in trouble: Kil’rek hits rather weak and does nothing out of the ordinary.
Talking about things out of the ordinary: Every 30 seconds or so, Illhoof will sacrifice a player that is not on top of his or Kil’rek’s hate list. This summons the player to the centre of the green circle, engulf him/her in Demon Chains and applies a very deadly, and undispellable, debuff that will damage the victim for 1.5k damage every second. As if this is was not bad enough, Illhoof is healed for large amounts while the Demon Chains are alive.
Sooner or later, Kil’rek will die to the damage done by the off tank. When this happens, Illhoof receives a debuff that will increase his damage taken by 25%. Heroism time! 
This debuff lasts for half a minute. After this time, Kil’rek will respawn and needs to be off tanked again.
Watch out for
Demon Chains! When someone is sacrificed, they need heals. Fast heals! And lots of them. As soon as a sacrifice is likely (more than 30 seconds after the last one) try to keep a Renew active on your assignment and be ready to Flash Heal any unlucky victim of the Demon Chains.
Side Note: Mages can use Ice Block and Paladins can use Divine Protection to escape the sacrifice.
If you want to regenerate mana with your Shadowfiend, wait until Kil’rek bites the dust. The 25% damage increase will net you a nice chunk of extra mana. Maybe enough to throw some damage on Illhoof yourself.
Healing Roles
The main tank needs a dedicated healer, he will be the target of Illhoof’s melee and Shadow Bolt attacks.
Additionally there will be a damage dealer that is tasked with controlling the adds. Ideally, this is a warlock that is spamming Seed of Corruption on Illhoof. This player will need a lot of healing, too. If you have a mage in your raid, have him cast Dampen Magic on the Nuker. It will help a lot.
The off tank will not take much damage and can be kept topped with an Renew most of the time.
Rewards
If you manage to keep the adds under control, the sacrifices short and the fight time below 10 minutes, you could be lucky to grab a Shadowvine Cloak of Infusion, a Mender’s Heart Ring or a Cincture of Will.
