Summoned by Gul'dan from the depths of the Twisting Nether, Xhul'horac is one of most powerful of the Void Revenants - a race of parasitic void-beings that tear holes through the planes of reality, consuming and absorbing the energies and beings within. Gul'dan has twisted Xhul'horac, feeding him overwhelming Fel energy, and using his powers to tear open the portals through which he plans to rally the forces of the Burning Legion.
Designer notes
A lot of our boss concepts for Hellfire Citadel began by imagining what would happen if we added fel energy to different parts of the Draenor ecology. What would a fel variant of one of the void revenants we saw a glimpse of in Shadowmoon Burial Grounds look like? Xhul’horac answers that question, and the mechanics of the encounter play off the different polarities of fiery fel energy and the shadowy void, which players must manage as they fight a creature with one foot (or tendril, as the case may be) in each realm.
Overview
Two portals dominate Xhul'horac's room: one powered by void, and one by the Legion's fel magic. Xhul'horac activates the Fel portal first, granting him fel abilities and summoning first Imps and then Vanguard Akkelion. When Akkelion dies, Xhul'horac activates the void portal, granting him void abilities and summoning Unstable Voidfiends and then Omnus. Once Omnus is defeated, Xhul'horac gains the energy of both fel and void, rapidly switching between elements. Once he reaches 20% health, he completely absorbs the power of both portals and must be quickly defeated.
Damage Dealers
Interrupt or intercept Fel Orb when you are not Voidtouched to avoid spreading Chaotic Felblaze.
When affected by Chains of Fel, move away from other chained players.
Close Black Hole by moving into its center, alongside other players to split the damage from Singularity.
Healers
When affected by Chains of Fel, move away from other chained players.
Close Black Hole by moving into its center, alongside other players to split the damage from Singularity.
Overwhelming Chaos will inflict heavy damage to the raid.
Tanks
When Xhul'horac gains Shadowfel Phasing, alternate which tank is hit by Void Strike and Fel Strike to avoid Shadowfel Annihilation.
Withering Gaze and Felblaze Flurry deal increasing damage each time they hit, and will drastically increase the damage of Void Strike and Fel Strike.
Falling off of Xhul'horac's platform is deadly! Beware the knockback from Void Strike and Fel Strike.
Abilities
Unleashed Energies
Throughout the encounter, Xhul'horac focuses the wild energy of fel and void in his summoning chamber, letting them smolder out of control - and mixing them with deadly results.
Feltouched — Players who take Fire damage within Xhul'horac's chamber become Feltouched as latent fel energies course through them. If a player takes Shadow damage while Feltouched, they will cause a Shadowfel Annihilation, and lose Feltouched.
Voidtouched — Players who take Shadow damage within Xhul'horac's chamber become Voidtouched as the void takes root within them. If a player takes Fire damage while Voidtouched, they will cause a Shadowfel Annihilation and lose Voidtouched.
Chaotic Felblaze — Creates a patch of chaotic felfire, which will spread over time. Players who touch the felfire will be afflicted by Felsinged. If Chaotic Felblaze spreads into Creeping Void, a Shadowfel Annihilation will go off at the location where they touch.
Felsinged — Inflicts 10000 Fire damage every 1 sec. for 8 sec. This effect stacks.
Creeping Void — Creates a patch of void which will spread over time. Players who touch the void will be afflicted by Wasting Void. If Creeping Void spreads into Chaotic Felblaze, a Shadowfel Annihilation will go off at the location where they touch.
Wasting Void — Inflicts 10000 Shadow damage every 1 sec. for 8 sec. This effect stacks.
Shadowfel Annihilation — The energies of Shadow and Fel react, unleashing a massive explosion. Within 20 yards, inflicts 161875 to 188125 Shadowflame damage and destroys any patches of Creeping Void or Chaotic Felblaze that it touches. Inflicts 23125 to 26875 Shadowflame damage to all other players. Targets within 20 yards take increased damage from further Shadowfel Annihilations by 100% for 2 min. Players who cause a Shadowfel Annihilation are stripped of Feltouched, Voidtouched, Blazing, Wasting Void and Felsinged.
Stage One: The Legion's Flame
Xhul'horac, tainted with Fel energy, summons forth servants of the Legion and attacks with Fel magic.
Fel Strike — Inflicts 323750 to 376250 Fire damage to Xhul'horac's current target.
Fel Surge — Fills several players with Fel energy, inflicting 25000 Fire damage every 1 sec for 5 sec. After the effect expires, affected players will create a small patch of Chaotic Felblaze.
Felblaze Flurry — A rapid series of strikes that each inflict 150000 Fire damage, and increase damage taken from Withering Gaze and Felblaze Flurry 50% for 7 sec. This effect stacks.
Chains of Fel — Tethers players together with fel chains, inflicting 25000 Fire damage every second per stack. Players gain a stack for each player they are tethered to. Affected players can move away from each other to break the chains.
Fel Orb — The caster conjures an orb of Fel fire. If the fire touches a player, they absorb it and are afflicted by Ablaze. If it travels too far without impacting a player, it will fall to the ground, creating a patch of Chaotic Felblaze.
Ablaze — Inflicts 45000 Fire damage every 1 sec. for 15 sec. This effect stacks.
Stage Two: Grasp of the Void
Xhul'horac opens the Void portal, summoning forth fellow Void creatures and drawing strength from the power of the Void.
Void Strike — Inflicts 323750 to 376250 Shadow damage to Xhul'horac's current target.
Void Surge — Fills a player with void energy, inflicting 62500 Shadow damage every 2.5 sec for 5 sec. When this effect expires, it will spread a large patch of Creeping Void.
Withering Gaze — Fixes his gaze on a player, inflicitng 375000 Shadow damage every 4 sec, and increasing damage taken from Withering Gaze and Felblaze Flurry 20% for 4 sec. This effect stacks.
Black Hole — Tears a hole in the fabric of reality, inflicting 33333 Physical damage to all players every 1 sec. and pulling them towards the Black Hole. If any player enters the Black Hole, they will unleash a Singularity.
Singularity — Inflcits 900000 Shadow damage divided among all players within 11 yards, and destroys the Black Hole.
Volatile Voidstep — Teleports to the nearest players location, inflicting 78625 to 91375 Shadow damage to any nearby players and spreading Creeping Void if the explosion contacts any players. On Mythic Difficulty, each cast of Volatile Voidstep will reduce the cast time of subsequent casts.
Stage Three: The Shadowfel Amalgamation
Overwhelmed by channeling a combination of Void and Fel energies, Xhul'horac's form begins rapidly shifting between one dominated by Fel and Void magic.
Shadowfel Phasing — Xhul'horac absorbs energy from the portals, rapidly shifting between Fel and Void powered abilities.
Empowered Chains of Fel — Once Akkelion is defeated, Xhul'horac absorbs his power, granting him Empowered Chains of Fel. Tethers players together with fel chains, inflicting 25000 Fire damage every second per stack. Players gain a stack for each player they are tethered to. Affected players can move away from each other to break the chains. Breaking Empowered Chains of Fel causes a Fel Snapback.
Fel Snapback — Inflicts 254375 to 295625 Fire damage to all players within 5 yards.
Empowered Black Hole — Once Omnus is defeated, Xhul'horac absorbs his power, granting him Empowered Black Hole. Tears a hole in the fabric of reality, inflicting 33333 Physical damage to all players every 1 sec. and pulling them towards the Black Hole. If any player enters the Black Hole, they will unleash a Singularity.
Empowered Singularity — Inflcits 900000 Shadow damage divided among all players within 8 yards, destroys the Black Hole, and increases damage taken from further Empowered Singularities by 1000%.
Fel Strike — Inflicts 323750 to 376250 Fire damage to Xhul'horac's current target.
Fel Surge — Fills several players with Fel energy, inflicting 25000 Fire damage every 1 sec for 5 sec. After the effect expires, affected players will create a small patch of Chaotic Felblaze.
Void Strike — Inflicts 323750 to 376250 Shadow damage to Xhul'horac's current target.
Void Surge — Fills a player with void energy, inflicting 62500 Shadow damage every 2.5 sec for 5 sec. When this effect expires, it will spread a large patch of Creeping Void.
Stage Four: Tearing Apart
Xhul'horac completely absorbs the energy of both the Void and Fel portals, preventing any new creatures from coming through them, and rapidly destabilizing.
Overwhelming Chaos — Overwhelmed by the combined energies of Fel and Shadow, Xhul'horac unleashes a burst of pure energy every 10 sec., increasing his damage dealt by 20% and inflicting 115625 to 134375 Chaos damage to all players. This effect stacks.
Strategy
Please add any available information to this section.
Voidscribe Aathalos is no longer susceptible to Charm, Possess, or Banish effects.
Weaponlord Mehlkhior, and other creatures around Xhul'horac are now immune to Charm effects.
Hotfix (2015-08-17):Omnus's Singularity damage can now be reduced by damage reduction effects on Raid Finder difficulty.
Hotfix (2015-08-11):Omnus's Singularity damage can now be reduced by damage reduction effects on Normal and Heroic difficulty. Note: A separate hotfix is in the works for this to also apply to Raid Finder difficulty.
Xhul'horac's Overwhelming Chaos now increases damage dealt by 15% (down from 20%) per stack on Normal difficulty.
Combat rogues should now be able to correctly use Killing Spree again after receiving the Empowered Singularity debuff.
Hotfix (2015-07-08):Adjusted scaling to reduce the amount of health by roughly 10% on Xhul'horac, Omnus, Unstable Voidfiend, and Vanguard Akkelion for a 10-player raid on Normal and Heroic difficulty. Health should remain the same as before for raids with 30 players.
Icy Veins Comprehensive Xhul'horac strategy guide (includes Heroic mode)
Xhul'horac
Damage Dealers
Healers
Tanks
Feltouched — Players who take Fire damage within Xhul'horac's chamber become Feltouched as latent fel energies course through them. If a player takes Shadow damage while Feltouched, they will cause a Shadowfel Annihilation, and lose Feltouched.
Voidtouched — Players who take Shadow damage within Xhul'horac's chamber become Voidtouched as the void takes root within them. If a player takes Fire damage while Voidtouched, they will cause a Shadowfel Annihilation and lose Voidtouched.
Chaotic Felblaze — Creates a patch of chaotic felfire, which will spread over time. Players who touch the felfire will be afflicted by Felsinged. If Chaotic Felblaze spreads into Creeping Void, a Shadowfel Annihilation will go off at the location where they touch.
Felsinged — Inflicts 10000 Fire damage every 1 sec. for 8 sec. This effect stacks.
Creeping Void — Creates a patch of void which will spread over time. Players who touch the void will be afflicted by Wasting Void. If Creeping Void spreads into Chaotic Felblaze, a Shadowfel Annihilation will go off at the location where they touch.
Wasting Void — Inflicts 10000 Shadow damage every 1 sec. for 8 sec. This effect stacks.
Shadowfel Annihilation 
— The energies of Shadow and Fel react, unleashing a massive explosion. Within 20 yards, inflicts 161875 to 188125 Shadowflame damage and destroys any patches of Creeping Void or Chaotic Felblaze that it touches. Inflicts 23125 to 26875 Shadowflame damage to all other players. Targets within 20 yards take increased damage from further Shadowfel Annihilations by 100% for 2 min. Players who cause a Shadowfel Annihilation are stripped of Feltouched, Voidtouched, Blazing, Wasting Void and Felsinged.
Fel Strike 
Fel Surge — Fills several players with Fel energy, inflicting 25000 Fire damage every 1 sec for 5 sec. After the effect expires, affected players will create a small patch of Chaotic Felblaze.
Felblaze Flurry 
Chains of Fel — Tethers players together with fel chains, inflicting 25000 Fire damage every second per stack. Players gain a stack for each player they are tethered to. Affected players can move away from each other to break the chains.
Fel Orb — The caster conjures an orb of Fel fire. If the fire touches a player, they absorb it and are afflicted by Ablaze. If it travels too far without impacting a player, it will fall to the ground, creating a patch of Chaotic Felblaze.
Void Strike 
Void Surge — Fills a player with void energy, inflicting 62500 Shadow damage every 2.5 sec for 5 sec. When this effect expires, it will spread a large patch of Creeping Void.
Withering Gaze 
Black Hole — Tears a hole in the fabric of reality, inflicting 33333 Physical damage to all players every 1 sec. and pulling them towards the Black Hole. If any player enters the Black Hole, they will unleash a Singularity.
Singularity 
Volatile Voidstep 
Shadowfel Phasing — Xhul'horac absorbs energy from the portals, rapidly shifting between Fel and Void powered abilities.
Fel Snapback — Inflicts 254375 to 295625 Fire damage to all players within 5 yards.
Overwhelming Chaos 
Please add any available information to this section.
[Voidthread Spineguard]
[Bracers of Tainted Magic]
[Girdle of Volatile Duality]
[Shadowfel Cord]
[Stoic Netherfel Legplates]
[Demonbreaker Crushers]
[Felfume Slippers]
[Ironpelt Boots]
[Rancorbite Sabatons]
Hotfix (2015-09-30):