Flame Leviathan

The Flame Leviathan is a boss found in the Ulduar adventure. He is the first boss of the adventure's first wing, The Siege of Ulduar.

Hero Power
For full information, see Flame Vents or Flame Vents (Heroic).

Deck
Note that the below classes are listed purely for reference, and have no effect on the Flame Leviathan's use of the cards in the encounter.

Starting Board
The Flame Leviathan does not begin with minions on the board in either Normal or Heroic mode. The player begins the game with a Salvaged Siege Engine and a Salvaged Demolisher in their hand.

Strategy
The Flame Leviathan's deck is composed entirely of Mechs and damaging spells, making a minion-based deck highly difficult to pull off. Its Hero Power, especially in Heroic mode, will put a quick stop to a deck composed of small minions, so it's best to let your vehicle's hero power and weapon protect you for the first few rounds. After that, you'll be able to start playing higher-cost minions. You can reap a lot of benefit from Deathrattle cards, as the Flame Leviathan will quickly be able to destroy almost anything you play.

Make sure to destroy any Mechwarpers the Flame Leviathan plays; they can turn its low-cost Mechs into almost free Mechs which will quickly flood the board. The large number of Iron Defenders in the deck can become highly dangerous while a friendly Mech is in play, so it's important to always kill things quickly. Use the Siege Engine's Electroshock Hero Power to handle some of the smaller ones, while saving spells like Frostbolt to deal with the larger ones.

Apart from Missile Barrage, Clockwork Giant, and Mimiron's Head, the Flame Leviathan doesn't really have any late-game cards, so once you've survived the first few rounds you've pretty much got it as long as you don't make any huge mistakes and maintain board control.

The Flame Leviathan's extremely high health means you need a fast, high-damage deck to defeat them before fatigue kills you. The Flame Leviathan's deck contains 40 cards rather than the regular 30, which means trying to give it fatigue before you is too much of a hassle to be worthwhile.

Flame Leviathan
Opening remark: Threat assessment protocol active.

Start of game: Threat assessment complete. Weapon systems activating.

Emote response: Reloading cannons.

Hero Power: Primary target engaged.

Cards:

Missile Barrage: Missile trajectories locked.

Battering Ram: Powering close-range weapons.

Player cards:

Flame Leviathan: Error. Illogical.

Defeat: Leviathan unit shutting down.

Brann Bronzebeard
Introduction: There's a massive engine blocking our approach!

Hero change: Now that you're in a vehicle, you might stand a chance.

On defeat: We've broken the defenses of Ulduar! Let's move on.