Cho'gall is the final boss in the Bastion of Twilight raid instance. He is being corrupted and if you want to take him down your raid will be too. Don't worry, with Learn to Raid's strategy guide, you'll have no problem fighting your way through the darkness. We'll show you how to take down this overgrown ogre like an advertisement for another Shrek movie.

L2R Difficulty Ranking = 2.6/5
– The encounter requires an appropriate amount of skill and gear for it’s progression placement. An average guild can expect a learning curve of 2-3 nights learning and executing this fight.
  • 3/5 - Tanking
  • 3/5 - Healing
  • 4/5 - DPS
  • 1/5 - Movement
  • 2/5 - Situational Awareness

Raid Makeup
  • Tanks – 2
  • Healers – 5 - 7
  • DPS – Balanced with many classes that can interrupt

Abilities: Phase 1
Conversion – Cho'gall beckons to the weak of mind causing the target to channel the worshipping spell on him.
Twisted Devotion – The Worshipping has caused Cho'gall to become more zealous, increasing damage done by 10% for 20 sec.
Flame's Orders – Cho'gall Orders the Flame to come to his aid. Adds 20,000 fire damage to each melee swing and spawns Fire patches.
Shadow's Orders – Cho'gall Orders the Shadow to come to his aid. Adds a shadow damage AoE that hits everyone in the room to Cho'gall's melee attacks.
Fury of Cho'gall - Cho'gall blasts the target, inflicting 30,000 Shadow and 30,000 Physical damage and increasing damage taken by Physical and Shadow by 20% each. Cast on primary aggro target. Lasts 45 seconds.
Summon Corupting Adherent - Cho'gall summons Corrupted Adherents to aid him.
Fester Blood - Festers the blood of any Corrupting Adherents, causing Blood of the Old God to form from congealed blood and boils the blood of living Corrupting Adherents.

Corrupting Adherent Abilities
Depravity – Inflicts 21937 to 23062 Shadow damage to enemies within 50,000 yards and causes Corruption. Interruptable. 1.5 second cast
Sprayed Corruption – Inflicts 34125 to 35875 Shadow damage in a frontal cone and applies Corrupted Blood.
Corrupting Crash – Fires a shadow missile at a target, dealing 43875 to 46125 Shadow damage to all enemies near the impact. Targets hit by the Corrupting Crash have corruption applied to them.
Spilled Blood of the Old God – The slain Adherent to the old god spills its corrupted blood. Inflicts 14625 to 15375 Shadow damage to enemies within 0 yards and applies Corrupted Blood.
Festering Blood - The Festered Blood is causing the Corrupting Adherent to bleed out and spray Corruption everywhere. Inflicts 43875 to 46125 Shadow damage every 2 sec and causes Corrupted Blood.

Abilities: Phase 2
Fury of Cho'gall – Cho'gall blasts the target, inflicting 30,000 Shadow and 30,000 Physical damage and increasing damage taken by Physical and Shadow by 20% each. Cast on primary aggro target. Lasts 45 seconds.
Corruption of the Old God – Cho'gall becomes completely corrupted by the Old Gods, inflicting 4875 to 5125 Shadow damage every 2 sec to everyone in the room.
Darkened Creations - Cho'gall summons Darkened Creations to aid him!
Debilitating Beam – Reduces healing and damage done by 75%. Inflicts 4875 to 5125 Shadow damage every 1 sec. Causes Corrupted Blood every 1 sec. Lasts 10 seconds. Undispellable.

Corrupted Blood
At the beginning of the fight, each member of the raid will have a UI element or graphic added to their screen that tracks their Corruption level. Throughout the fight, the abilities Cho’gall and his adds use will cause stacks of Corrupted Blood. Raid members will be afflicted with varying debuffs depending on how high their Corrupted Blood is. This mechanic is similar to Madness from the Yogg’Saron encounter and at least initially should be approached the same way. Avoid gaining Corrupted Blood at all costs. Here are the debilitations raid members will gain as their debuff grows.
At Level 1 (25%) players will gain Corruption: Accelerated. This will cause them to gain 2 stacks of Corrupted Blood every second for one minute. This is magic dispellable and should be removed immediately. At level 2 (50%) players will be afflicted with Corruption: Sickness. This will cause them to periodically vomit and cause 40k damage to all friendly players in a 5 yard cone in front of them. This vomit will also cause Corrupted Blood. Players must be sure to face away from other raid members before vomiting. At level 3 (75%) players will gain Corruption: Malformation. A tentacle will grow out of the players back and shoot shadowbolts at nearby raid members. At level 4 (100%) players are afflicted with Corruption: Absolute. They will receive 100% less healing, but do 100% more damage. Spells will also be instant cast. Now that we’ve covered the main mechanic of the fight, let’s go over Cho’gall’s abilities.

During phase 1, the boss should be tanked in the middle of the room with ranged in a stacked group behind him. Adds will be tanked on top of the boss before being moved to the back of the room to die. Occasionally, the boss may need to moved further forward toward the throne in order to allow more time to kill adds. In phase 2, the dps splits into groups in a square formation to better cover Darkened Creations. Healers can remain where the original stack point was and the boss does no need to be moved.

Strategy - Phase 1
Our phase 1 positioning is very simple. The boss is tanked in the middle of the room, facing toward the throne. Melee attack from his rear while ranged stack in another pile behind the boss. One of the first things your raid must figure out is how Conversion is being handled. We used mages to Dragon’s Breath on top of the raid. With good timing, this instantly breaks all of the mind controls without allowing Cho’gall to gain any stacks of Twisted Devotion. If you raid is light on mages, Psychic Scream is a great option. Any series of counterspell like abilities will also work, but are single target of course. Because the raid moves somewhat together during this phase, we put our tank healers (two pallies in this case) on the sides of the group. This means tank healers should have to move less and be more easily able to maintain healing on the tanks. Because they are out of the raid however, 2 of our mages are assigned to counterspell the tank healers if they are converted. Flame’s Orders and Shadow’s Orders are easy to deal with, simply direct more healing to the tank or raid accordingly. Tanks should make sure to be vocal taunt quickly after gaining the Fury of Cho’gall debuff. When Cho’gall summons a Corrupting Adherent, the offtank should pick the add up and drag it next to the boss. While the add is up, the raid must be cautious to not be hit by any Corrupting Crashes. There is a large purple swirling graphic on the ground where the crash will land that gives approximately a 3 second warning. During this add phase it is not uncommon for the raid to spread out a little bit for crashes, but whenever possible players should stack back up to make interrupting Conversion and healing easier. Make sure to assign two interrupters to the add so that it does not cast Depravity on the raid. Ranged DPS should focus on the add, while melee classes cleave damage between the Adherent and the boss. When the add reaches a low percentage, we used 15%, the tank should begin dragging him to the back of the room away from the raid. Ranged can continue to DPS him, but do not kill the add until it is in the back area. During this move to the back of the room, the add may still cast Depravity. Have 2 ranged dps ready to counterspell the add since melee will be out of range. Ideally, the add should make it to the back of the room just as it dies. Here you can see I Leap of Faith the tank back to raid in order to minimize the Corruption stacks he gains. This isn’t entirely necessary, but if you choose to do it, know that this ability will be up for every add phase. Thirty seconds after the add has spawned, Cho’gall will use his Fester Blood ability. Ideally, the add is dead at this point and 5 Blood of the Old God adds will spawn out of the blood he’s left behind. Use hunter traps, knockbacks, and any other snares to keep these from reaching the raid. Ranged dps should AoE them down. Think of these like adds from the Saurfang encounter. Slow them and root them before they reach the raid and kill them. Once the adds are down refocus all the raid’s DPS on Cho’gall. That’s an entire cycle of phase 1. It’s important to keep Corruption stacks low because this will help your raid survive longer in phase 2. Repeat this until the boss’ health reaches 25% and prepare for the next part of the encounter.

Strategy - Phase 2
Positioning for phase 2 is a little different than phase 1. We split our raid into 4 dps piles with healers occupying the middle. The boss is still tanked in the same spot, but because Darkened Creations spawn randomly in a circle around him, splitting the raid up allows them to be killed quicker. Have raid members focus on the Creations closest to them first then assist with any still alive. Only DPS the boss after all Creations have been killed. It should not take very long to kill all of the creations with correct targeting. Healing in this phase will go up over time as the raid’s corruption stacks increase, but by handling the mechanics correctly this phase can still feel stable. Make sure to dispel Corruption: Accelerated immediately, as it will be being applied to the raid very quickly in this phase. People with Corruption: Sickness should make sure to face away from the raid so they do not vomit on other players. Overall, this phase is a dps race. You’re trying to kill Cho’gall before your entire raid either dies or is Corrupted. If you can handle all of the abilities and switch targets at the right times, this should be easy.

Discuss the fight more in it's forum thread here.