Nefarian and Onyxia Guide with Cheap Decks for Blackrock Mountain

Last updated on Apr 30, 2015 at 17:08 by Sottle 93 comments

Table of Contents

Nefarian and Onyxia are the fourth and final boss of the Hidden Laboratory, the fifth and final wing of Blackrock Mountain. In this guide, you will learn how to use cheap decks to defeat Omnotron in both Normal and Heroic modes.

Nefarian Normal Nefarian Heroic
Onyxia Normal Onyxia Heroic

Health, Hero Power, Cards, Etc.

Normal Heroic
  • Nefarian: 30 (+10 Armor)
  • Onyxia: 15
  • Nefarian: 30 (+30 Armor)
  • Onyxia: 30
Hero Power Nefarian's Hero Power is Bone Minions. It costs 2 Mana and summons 2 2/1 (4/2 in Heroic Mode) Bone Constructs. When Nefarian's armor is removed, Onyxia takes his place as your opponent. She has a 2/6 Weapon equipped and Her Hero Power is Nefarian Strikes!, which causes Nefarian to attack you for a random amount of damage. After Onyxia dies, Nefarian destroys all your minions and retakes his place as your opponent.

Strategy and Deck Building

Nefarian is a fight that takes place in three phases. The first phase is a battle with Nefarian himself, and lasts until you deplete his armor. At this point, he summons Onyxia to replace him and hovers over the battlefield dealing damage to you on each turn.

The second phase of the fight is a battle with Onyxia, and ends once you have depleted Onyxia's health. During this phase, Onyxia will have a weapon equipped that should be dealt with quickly. Once you enter the third phase, where Nefarian re-enters the battle, your board will be wiped clear. You should prepare for this phase by making sure you have enough cards in hand to follow up the board clear. Kel'Thuzad is particularly powerful here since it can revive all the minions that are destroyed.

To help you build your decks and defeat Nefarian and Onyxia in both modes, here are decks we defeated him with: