Terestian Illhoof is a corrupted satyr boss located within the Repository of Karazhan, hidden within a secret passage behind a bookshelf within the library.  Although an optional boss to slay, Terestian possesses loot often making his demise worthwhile.

Abilities

Melee – Around 1800 per hit on the tank.

Shadow Bolt – Fired at the highest target on the threat list, deals about 4000 damage.
Sacrifice – A random character will be targeted and summon to the center of the room, paralyzed there.  The afflicted player will begin to suffer 1500 unresistable and unabsorbable shadow damage per second until the chains are destroyed.

Whilst the chains are still present Illhoof is healed for 3,000 health per second.  The chains themselves have somewhere around 13,000 health and can be removed by either Divine shield or Ice Block.

Berserk – After ten minutes have passed Illhoof will go berserk, spamming extremely damaging shadow bolts on the entire raid every couple seconds.

Kil’rek

Melee – Around 2000 to clothies, otherwise much less.

Amplify Flames – An unremovable debuff that increases fire damage taken by 500, randomly targeted.

Broken Pact – Debuff to Illhoof, causing him to take 25% more damage until Kil’rek respawns(45 seconds later.)

Fight

The fight in general will be decided based upon good AoE and the ability for players to break off and destroy the chains/heal the chained player as quickly as possible, however this must be without neglecting other duties such as dropping the boss himself.

Once the boss is pulled about 10 seconds will pass before he emotes and summons two portals into the back of the room.  Imps will pour out from within the portals at a continual pace throughout the fight.

Kil’rek, the bosses imp familiar, will respawn about 45 seconds after being slain.  The other imps can be dealt with by utilizing AoE, keep the boss within range to deal some damage to him on the side.

Tanking

In general this fight should require either one Paladin tank or possibly two warriors/druids to deal with, the reason being the paladin’s considerable AoE tanking capabilities allowing him/her to hold both the imps and the boss at once.

Should you decide to utilize a Paladin tank make certain that he or at least a paladin within his team has the fire resistance aura going, it aid’s dramatically over the course of the entire fight, reducing the imps damaging fireballs by a decent amount.

Kill Priority

The priority target for this fight will be the Demon Chains as soon as they appear.  This obviously would be due to the double entendre of healing the boss, which is very bad, as well as damaging one of the raid members continually thus draining healer mana, which is also quite bad.

After that second priority would be dropping the ever annoying, and resurrecting, Kil’rek.  In general it’s best to try and drop this guy within about 10-12 seconds of DPS, anything more is going to make him a pain due to drawing damage too long from the boss himself, if so possibly AoE can drop him gradually while the tank soaks his damage.

The simple trash mob imps can, as said above, be either AoE’d down as fast as possible by Warlocks, seed of corruption, or mages, otherwise a well-geared rouge/feral druid can burn them as well.

Sacrifice

One common strategy to deal with keeping the sacrificed target alive is to utilize the target of target function to follow Illhoof’s aggro, the sacrifice cast is targeted around 3 seconds prior to actually being sacrificed therefore giving time to begin heals.

Paladins and mages can utilize Divine shield and Iceblock, respectively, to escape from the chains immediately.  Another trouble is when the player AoE’ing the imps is sacrificed, resulting in the imps running wild on healers and other such players until the player is freed.

Finally, tanking Illhoof next to the sacrifice circle will allow melee to easily switch targets and drop the chains before returning to the boss.