Omnotron Defense System Encounter Guide: Strategy, Abilities, Loot

• Save major cooldowns for when you face Arcanotron and can stack in his Power Generator.
• This fight has a lot of stacking and spreading mechanics, do not greed for damage here, move quickly when you need to.
• Be ready with personal defensive cooldowns if you are targeted by Flamethrower.

• Coordinate defensive and healer cooldowns when fighting Electron as he deals massive AoE damage.
• On heroic difficulty, a Priest should be ready to use Leap of Faith on the Lightning Conductor target when they get debuffed with Shadow Infusion to quickly pull them into the raid.
• If DPS take too many stacks of Soaked In Poison you can dispel the entire stack of poison with only one dispel.

• When a boss activates its shield at 50 energy, drag it away from the raid to stop players from attacking it.
• If Arcanotron is active, quickly position the current target next to the Power Generator to allow your melee DPS to benefit from it as well.
• If Toxitron is active, quickly drag the current target into the Chemical Cloud poison to increase their damage taken by 50%.

On this encounter you will be fighting four bosses, Arcanotron, Electron, Magmatron, and Toxitron with a shared health pool. At the start of combat you will only be fighting one of these golems; it will have 100 energy, which quickly drains as soon as they enter combat. When their energy reaches 50, they will shield themselves and activate another of the bosses. When their energy reaches 0, they become inactive for a short while. This newly activated boss will follow the same pattern, starting with 100 energy, quickly draining over time, activating another boss at 50 energy and shielding self, and finally completely deactivating at 0 energy. Each boss will continue to use their abilities while at 50 energy, meaning you will need to constantly deal with two bosses mechanics at a time. This is the main structure of this fight, constantly changing targets roughly every 30 seconds.

Magmatron is one of the harder out of the four bosses. He will hit the entire raid with Incineration Security Measure, dealing high Fire damage over 4 seconds. He will also occasionally mark someone with Acquiring Target and shortly after use Flamethrower on the marked target, dealing high Fire damage to all targets in front of him. The player marked with Acquiring Target must move away from everyone else while the raid makes sure they are behind the boss and use a defensive cooldown on the Acquiring Target player to ensure they survive. On heroic difficulty Lord Victor Nefarius will assist in the fight and use Encasing Shadows on the Acquiring Target victim, rooting them in place. Remove this with Hand of Freedom or have the entire raid move away from this player. When Magmatron reaches 50 energy it will protect itself with Barrier, absorbing damage; if the Barrier is broken with enough damage he will wipe the raid. Simply swap to the new boss and avoid hitting Magmatron whenever he shields himself with Barrier.

Arcanotron is the easy boss out of the four, and will even buff your raid with increased damage done and mana regeneration. He will frequently cast Arcane Annihilator, which must be kicked or it will hit a random player for about 80,000 Arcane damage. Arcanotron will spawn a Power Generator on a random player, buffing the damage of everyone inside by 50% and restoring mana. On heroic difficulty Lord Victor Nefarius will assist on the fight by using Overcharged Power Generator, increase the damage buff while inside the field to 100% and restoring even more mana, but causing the power field to grow in size and eventually explode with Arcane Blowbackm killing anyone in the area. When Arcanotron reaches 50 energy he will shield himself with Power Conversion, converting damage taken into stacks of Converted Power, increasing his Arcane damage and spell haste by 10% per stack. You can continue to hit Arcanotron with cleave damage and DoTs as long as you purge these stacks quickly, or have a Mage Spellsteal them for the haste buff.

Electron is the Lightning based boss and deals a ton of AoE raid-wide damage. Electrical Discharge deals Lightning damage to three nearby enemies and bounces to other nearby allies, increasing the damage dealt with each bounce. Have the melee DPS spread out around the boss evenly, and if you have melee heavy split them up into groups around the boss to prevent this from bouncing more than once with ranged and healers stacking nearby. Electron will target a random player with Lightning Conductor, causing them to deal high damage to all nearby allies. This player must move away from the raid quickly; on heroic difficulty, Lord Victor Nefarius will randomly debuff the Lightning Conductor target with Shadow Infusion, causing them to deal raid-wide damage. The damage from Shadow Infusion is increased the further that the target is away from the raid, meaning they will need to quickly stack back up even while they still have Lightning Conductor. Be ready with raid-wide defensive or healer cooldowns to survive this. After 5 seconds, both Lightning Conductor and Shadow Infusion will be removed and replaced with Shadow Conductor, which will continue to deal raid-wide damage, increased by how far away players are from the debuffed target. When Electron reaches 50 energy he will use Unstable Shield, dealing massive AoE Lightning damage if he is attacked; simply swap off this and do not cleave him.

Toxitron is the fourth and final boss in the encounter. He will cover random areas in the room with Chemical Bomb, leaving a Chemical Cloud of poison on the ground. Anyone inside the Poison cloud will take 50% increased damage as well as Poison damage over time. Drag the boss that you are attacking into the Chemical Cloud to increase their damage taken by 50%. On heroic difficulty, Lord Victor Nefarius will occasionally use Grip of Death to pull the entire raid into one of the Chemical Clouds; you must quickly move out of this and reposition. When Toxitron casts Poison Protocol he will create multiple Poison Bomb oozes that will Fixate on a random player and chase them down. If they reach their Fixate target they will kill them and any nearby allies, and create a Poison Puddle on the same spot. Slow the Poison Bomb oozes down and quickly focus them down to prevent deaths. Lastly, when Toxitron reaches 50 energy he will gain Poison Soaked Shell. Attacking this shield will cause you to become Soaked In Poison, dealing 20,000 Nature damage every 2 seconds, stacking up each time you attack the Poison Soaked Shell. You can consume these Poison stacks by attacking a different boss thanks to Expunge Poison, dealing additional damage to the target. Be mindful of your stacks and try not to over do it and overwhelm your healers.

The most difficult part of this encounter is dealing with multiple bosses mechanics at a time. Since the boss that spawns is random, it is possible to get any two bosses at once, with some combinations being very easy, and some being very difficult. Electron and Magmatron up at the same time is by far the most difficult combo as they both deal very high raid-wide damage with Incineration Security Measure, Electrical Discharge, Lightning Conductor, Shadow Infusion, and Shadow Conductor. Rotate multiple raid-wide defensive and healer cooldowns if you get this combo to survive the damage. Be aware of what each boss does and understand what abilities you need to deal with for the current boss combo and you will beat this boss easily.

Achievement	Description
Achieve-a-tron	Defeat the Omnotron Defense System in Blackwing Descent while neutralizing the following attacks.
Heroic: Omnotron Defense System	Defeat the Omnotron Defense System in Blackwing Descent on Heroic Difficulty.

Omnotron Defense System is just one of the six encounters present in the Blackwing Descent raid of Cataclysm. If you would like to learn more about the others, please see our other pages for the raid below.