Hearthstone Blackrock Mountain - Hidden Laboratory Strategy

I have beaten the final wing of Hearthstone Blackrock Mountain Hidden Laboratory Normal Mode the same night it was released. With that, I have obtained all the Blackrock Mountain and class cards. I walk the talk and I will guide you to get more Legendary cards without purchase.

The final wing Hidden Laboratory bosses were all beaten with one class, namely Priest. The reason, the computer either had 2 silence cards or 2 removal cards in their deck. It is very easy to take advantage of it even when playing against real players. When both cards are used up, you just need to buff one taunt card to very high health and there is no way they can get pass it. So the win condition will be to buff a Deathlord to extreme high health with even free Power Word Shields, Divine Spirit, Dark Cultist (Nax). I was lucky to have 1 Velen's Chosen, 1 Temple Enforcer and 1 Inner Fire with the free decks from those quests of spectating a friend win. Finally, a Kel'Thuzad to repeated revive your Dark Cultist and Temple Enforcer and buff your minions health to seal the victory.

Omnotron Defense System

Hero Powers (Normal) -
Activate Arcanotron! (2 mana)
Activate Toxitron! (4 mana)
Activate Electron! (6 mana)
Activate Magmatron! (8 mana)
Activate! a random tron! (4 mana)

Hero Power (Heroic) -
Activate Arcanotron! (0 mana)
Activate Toxitron! (2 mana)
Activate Electron! (4 mana)
Activate Magmatron! (6 mana)
Activate a random tron! (2 mana)

I chose Priest due to past experiences. First try and I was successful. I put in all my favorite free spells like Holy Smite, Holy Nova as damage would +2 for Arcanotron and cost -2 for Electron. Also removal and buff spells. Their Toxitron will help you to AOE 1 damage but your hero healing power is 2. I saw in gamepedia the boss deck had 2 Earth Shocks and no removals. So if they do not draw Earth Shock and you buff your Deathlord (Nax) to oblivion and Inner Fire, it will be a textbook boss win.

I saw in other sites like gameskinny recommended Warrior as well. I believe it will work as Toxitron will buff your enrage minions or multiply your Grim Patron.

Recommended Class: Priest/Warrior
Recommended Cards: Holy Smite (F), Holy Nova (F) Northshire Cleric (F), Dark Cultist (Nax), Divine Spirit (F), Power Word Shield (F), Shadow Words (F), IBO, High Health Minions, Kel'Thuzard (Nax), Inner Fire, enrage minions, Gurubashi Berserkers

Maloriak

Hero Power (Normal) - Whenever a minion is summoned, swap its Attack and Health. (0 mana)

Hero Power (Heroic) - Minions' Attack and Health are swapped. Your minions have +2/+2 (0 mana)
Again I tried Priest buffing Deathlord or Dark Cultist or Snapjaw and it was successful. Hell, perhaps 9/5 Core Hound will work too. I was thinking Crazed Alchemist will work too. Textbook win again. I believe Paladin will work too as the boss power is very similar to a previous Blackrock wing stage.

Recommended Class: Priest/Warrior
Recommended Cards: Northshire Cleric (F), Dark Cultist (Nax), Divine Spirit (F), Power Word Shield (F), Shadow Words (F), IBO, High Health Minions, Kel'Thuzard (Nax), Gurubashi Berserker (F), Core Hound (F), Crazed Alchemist, Inner Fire

Atramedes

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

Hero Power (Heroic) - Equip a weapon that grows as your opponent plays cards. (0 Mana)
Same style Priest. They give you 3 Gongs to destroy their weapons in normal mode. If you are worried, equip 2 more Acidic Swarm Ooze. If you have Harrison Jones, you can draw a few cards too. Destroy it when the weapon gets sufficiently high in attack. Deathlord taunt buff trick works all the time as gamepedia listed out his deck has no removals. Gameskinny recommended Mech Mage to freeze his minions and him with Snowchugger and Water Elemental and stall for Acidic Swarm Ooze. It's kind of getting boring, isn't it.

Recommended Class: Priest/Mech-Freeze Mage
Recommended Cards: Northshire Cleric (F), Dark Cultist (Nax), Divine Spirit (F), Power Word Shield (F), Shadow Words (F), IBO, High Health Minions, Kel'Thuzard (Nax), Gurubashi Berserker (F), Acidic Swarm Ooze (F), Inner Fire.

Nefarian / Onyxia

Hero Powers (Normal) -
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)

I used Priest to clear it first time. I thought it was no challenge, until it wiped out my high level minions including my buffed Deathlord, Temple Enforcer and Kel'Thuzad when he changed his final form back from Onyxia to Nefarian. That made my hearth skipped a beat. Nevertheless, I regained my composure and finished him off. The most crucial thing here is to reduce his armor to as close to 1 as possible while building up your high health/high attack minion which can be Deathlord (Nax) preferably, Kel'Thuzad (Nax), Dark Cultist (Nax) or any high health minion like Oasis Snapjaw. Deathlord will be preferred as it has taunt. You need to 1-shot KO Onyxia, meaning your total attack has to be 31 or higher. You do this by Power Word Shields, Divine Spirits, repeatedly buff with Dark Cultist, Velen's Chosen, Temple Enforcer and Inner Fire if you have any, preferably with Kel'Thuzad constantly reviving them behind the Deathlord taunt wall. Watch out for Kel'Thuzad less he get killed by spells. I saw some people from other forums used Light of the Naaru to summon a Lightwarden instead, since they could not draw the right combo and also the hero heal power buff their attack. I repeat here again. DO NOT break Nefarian's armor and get close to 1 armor, but be careful of your own Holy Nova, and 1-SHOT KO him.

Good Luck!

Update: I used the Dragon deck with Paladin but it has a very high mana curve. Unless you have Muster for Battle, Implosion or AOE to clear minions or kill your minions then call out the Drakes, it is very difficult to use.