How to beat Hearthstone's Omnotron Defense System, Maloriak, Atramedes, and Nefarian in Blackrock Mountain's final wing, Hidden Laboratory.

Hearthstone Blackrock Mountain – Hidden Laboratory Guide

How to beat Hearthstone's Omnotron Defense System, Maloriak, Atramedes, and Nefarian in Blackrock Mountain's final wing, Hidden Laboratory.
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Blizzard’s online card game, Hearthstone, has come out with a brand new solo adventure for players to test his/her strength against a variety of bosses.

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The newest journey, Blackrock Mountain, features 5 different wings with 3-4 bosses each. Each boss can be beaten on normal or heroic mode, with card rewards, class challenges, and more. 

Here we explore the fifth (and final) wing of the series, Hidden Laboratory, as we explore the next 4 bosses and the best classes, cards, and strategies to beat them. 

Omnotron Defense System 

Omnotron Defense System is the first boss fight in the Hidden Laboratory, and is essentially an array of different Mech minions standing in your way. Just like its World of Warcraft counterpart, this fight is a rotation of different hero powers spawning different “Trons,” that have different effects on the battle.

Health: 30

Health (Heroic): 30

Hero Powers –  

Activate Electron – Activate Electron! (6 mana)

Activate Toxitron – Activate Toxitron! (4 mana)

Activate Arcanotron – Activate Arcanotron! (2 mana)

Activate Magmatron – Activate Magmatron! (8 mana)

Activate! – Activate a random tron! (4 mana)

Hero Power (Heroic) –  

Activate Electron – Activate Electron! (4 mana)

Activate Toxitron – Activate Toxitron! (2 mana)

Activate Arcanotron – Activate Arcanotron! (0 mana)

Activate Magmatron – Activate Magmatron! (6 mana)

Activate! – Activate a random tron! (2 mana)

Special Cards



General Strategy

This boss fight is very control heavy, as each different “Tron,” has its own special power, such as lower mana cost for spells, damaging all other minions, etc. The main point to keep in mind here is that the minions benefit you as well, so by countering this control deck with your own, he’ll be helping you every step of the way.

Common control classes, like Priest and Warrior, will easily bring this Defense System to its knees. 

Recommended Classes

Priest – The popular control Priest deck contains basic removal spells like Holy Smite, Power Word: Shield and Death, and Holy Nova. These removal spells work perfectly against this boss because of the spell power and reduced cost that Electron and Arcanotron give you throughout the fight.

It also contains minions like Northshire Cleric, which is perfect against Toxitron for constant heals and draw power, Deathlord, to keep control on your side of the field, and Cabal Shadow Priest for ALL OF THE CONTROL!

Paired with heals that all cost less, there’s no way to lose.

Warrior – The Warrior suggestion is based on the same control premise as the Priest. The armor control Warrior deck making its way around the meta is another perfect counter to this deck with spells like Brawl and Whirlwind. These spells will be buffed by the “Trons” as well. 

The enrage minions that this deck plays will work well with Toxitron, as it will only damage them for 1, triggering the maximum value. Alongside the infamous armor stack with cards like Armor Up! and Armorsmith, it’s doubtful you’ll lose control. 



Maloriak is an alchemist boss that uses a unique playstyle based on his hero power. Basically, every minion either of you spawn will swap health and mana, and in heroic mode his minions will gain +2/+2. 

Health: 30

Health (Heroic): 30

Hero Power – The Alchemist – Whenever a minion is summoned, swap its Attack and Health. (0 mana)

Hero Power (Heroic)  – The Alchemist – Minions’ Attack and Health are swapped. Your minions have +2/+2 (0 mana)

Special Cards

General Strategy

You may be seeing a reoccurring theme here, but the best way to approach this boss is by using his hero power against him. This fight is another control-based fight easily won by using creatures with large amounts of health. These minions will turn into huge fighters because of Maloriak’s passive. 

When you think of fat creatures, Druid immediately comes to mind. The same control Priest deck from last fight is another great control option against this boss.

Recommended Classes

Druid – Ramp Druid decks are perfect here, minions like Druid of the Claw and Ancient of War can be used to get taunts with lots of attack power. Buff cards will play into this hand nicely as well, like the infamous Savage Roar and Force of Nature combo. 

Druid also has a decent amount of heals and removal spells, like Swipe, to remove the 1/1 taunts that he spawns while still retaining value. 

Priest – Using the same approach as last fight, a control Priest deck with spells like Power Word: Shield, Pain, and Death. The extra health here is also huge with minions such as Northshire Cleric, who will have higher attack power and lower health than normal. 

Unfortunately, the Lightwell will be useless because it will automatically die when placed on the field, but this can be made up for in other ways, like Holy Nova and Circle of Healing. 



Atramedes is a blind dragon that uses your cards against you. Every card you play makes him more and more powerful; thus you should use caution for the first few turns for this wing.

Health – 30

Health (Heroic) – 30

Hero Power – Echolocate – Equip a weapon that grows as your opponent plays cards. (1 Mana)

Hero Power  – Echolocate – Equip a weapon that grows as your opponent plays cards. (0 Mana)

Special Cards

Player Cards

General Strategy

Since Atramedes is blind, he uses his other senses to find you and beat you that way. For example, the more cards you play, the stronger he becomes (a.k.a. your footsteps or your smell). He equips a weapon early on that will gain attack power the more cards that you play, so a carefully crafted deck with some weapon removal will come in handy. 

Any mid-range deck will beat his normal cards, but you’ll need to substitute two of your normal minions with the Acidic Swamp Ooze. This minion is infamous for removing your opponent’s weapon, paired with a Mage or Priest control deck, he won’t stand a chance. 

Recommended Classes

Mage – The Mage’s freeze capabilities will come in handy here when you need to buy some time for your Acidic Swamp Ooze to show up, or to gain control in moments of weakness. 

The popular Mage control deck right now is Mech Mage, which includes many Mech minions that feed off and buff each other, as well as Mage-exclusive minions such as the Snowchugger and Water Elemental. 

Priest – Priest control is practically the best type of control deck in the current meta, which is why it’s been rearing its head so frequently in this article. As I previously mentioned, the control Priest deck contain minions such as the Northshire Cleric for early game presence and draw power, and the Cabal Shadow Priest to gain an advantage in tight spots.

It also includes removal spells like Holy Smite and Holy Nova. The main reason Priest decks work so well against bosses is their hero power, Lesser Heal.


Nefarian / Onyxia 

Nefarian is the last boss fight for Blackrock Mountain and a 2-part fight for players. The first stage of this fight is to beat Onyxia, who has 15 health in Normal mode and 30 in Heroic mode. 

Health – 30

Health (Heroic) – 30

Hero Powers –  

Nefarian Strikes! – Nefarian rains fire from above! (0 Mana)

Bone Minions – Summon two 2/1 Bone Constructs. (2 mana)

Hero Powers (Heroic) – 

Nefarian Strikes! – Nefarian rains fire from above! (0 Mana)

Bone Minions – Summon two 4/2 Bone Constructs. (2 mana)

Special Cards


General Strategy

This fight against Onyxia and Nefarian follows suit with the strategy of the other boss fights in this wing, and requires a control deck for completion.

With low-cost AOE cards like LAVA!, which does 2 damage to all minions, aggressive decks with weaker minions will just be wiped out. Therefore, the key to this fight is to maintain control and to beat boss bosses the old fashioned way.

Recommended Classes

Hunter – Mid-Range Hunter is just enough aggression with just enough control and removal. The constant pressure from cards like Snake Trap, Animal Companion, and Eaglehorn Bow, you’ll force these bosses to take the defensive.

Removal spells like Arcane Shot, Explosive Trap, and Unleash the Hounds is another crucial aspect of this deck so that you can easily take care of your opponent’s creatures.

Mage – As I mentioned before, it’s extremely hard to beat a control Mage in the current meta, and these bosses are no exception. With all the mech cards playing off of each other, like Annoy-O-Tron, Cogmaster, Mechwarper, etc., paired with freeze cards like Snowchugger, Frostbolt, and Water Elemental, it’s going to be difficult for your opponent to gain the upper hand.

Remembering your burn spells like Fireball, and secrets like Mirror’s Entity, the chances of you losing control are slim to none. 

It’s also worth noting that the Druid and Priest decks from previous fights in this wing will also carry over well into this fight. 


Wing Completion

Completing the entire wing will grant you the legendary card, Nefarian:

Head back to our Blackrock Mountain Landing Page for other guides. 

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Danielle Marie
All I'm saying is, no one's ever seen me and Batman in the same room.