Frostwyrm Lair is the fifth and final wing in the Hearthstone expansion Curse of Naxxramas.  In it you will only find two bosses, but they are the final two and some of the nastiest in the expansion. This guide walks your through each boss’s basic abilities, what to expect, and what your reward will be for defeating them.

The bosses are as follows:

  • Sapphiron
  • Kel’Thuzad


Sapphiron is the second last boss on the Curst of Naxxramas expansion.  He is a huge ice dragon that can destroy almost anything with his hero power called Frost Breath.  At the start of each turn Sapphiron will use Frost Breath for no mana and destroy all enemy minions that are not frozen!

Ok, don’t panic too much, on normal mode you get a 2/10 Frozen Champion minion that starts on the board and protects any adjacent minion from Frost Breath.  Sapphiron will attack this minion though so you need to work quickly or it will be destroyed and then so will all your minions.

Being ice based it should come as no surprise that Sapphiron makes use of ice cards from the Mages card list.  You can expect to see blizzard, cone of cold, ice lance, frostbolt, and more.

Once you defeat Sapphiron you will be rewarded with two Echoing Ooze cards as shown above.

NOTE: It is important to note that Alexstraza cannot be used in this fight.

Sapphiron Strategy

There are a few ways to go about this fight, the best two in my opinion though are to either rush Sapphiron down with an agro deck before he can kill off the Frozen Champion, or to control the pace and keep the champion alive to kill Sapphiron off in the late game.

Many different decks can accomplish the agro beat down method.  Zoo, Hunter Aggro, Murloc, and Shockadin all work very well if you can put together a set of draws that will kill him off in about 6 turns.  It takes some luck of the draw but is completely doable.

The second method works by keeping at least one taunt minion up and next to the frozen champion so that he is not hit by too much damage.  You can also use cards or the Priest hero power to keep the frozen champion healed and alive.  By doing this you can keep the frozen champion alive right to the end of the game and deal with Sapphiron in any method you chose.

Heroic Mode - When attempting this fight in heroic mode it is much more difficult due to the fact that you will not be provided a Frozen Champion and therefore all your minions will die the turn after they come into play.

This means that in heroic mode you need to build very specific deck styles to be able to cope with Sapphiron.  Many players have luck with direct damage based decks that have few minions.  Minions that do work well are those with powerful deathrattle abilities such as Mad Scientist and Nerubian Egg, or minions with charge like Leeroy Jenkins, Arcane Golem, Unleash the Hounds, and more.


The last boss of the Curse of Naxxramas expansion for Hearthstone is the mighty Kel’Thuzad.  Prepare yourself, as this will be a long and difficult encounter that is made up of two phases.

Kel’Thuzad starts the battle with 30 health and 20 armour and a hero power called Frost Blast.  This power deals 2 damage to you and freezes you, and does not cost any mana.

Once you have destroyed Kel’Thuzads 20 points of armour, he will interrupt the fight and the second phase of the fight will begin.  He will lose his Frost Blast power but gain a much nastier one called Chains which costs 8 mana but gives him control of a random enemy minion until the end of the turn.  He will use this to kill off your own minions with your other minions.

Kel’Thuzad makes use of many different class cards including some from Warlocks, Priests, Mages, and Shamen.  Be prepared for a bit of everything.

By defeating Kel’Thuzad you will earn 2 copies of the Shade of Naxxramas minion card shown below, as well as a copy of Kel’Thuzad himself in card form.

Kel’Thuzad Strategy

One of the most important things with this fight is planning it properly.  The switch from phase one to phase two is a hard interruption of the fight, meaning no matter how many other things you would like to do, as soon as he looses that last point of armour, the phase (and your turn) ends.  Kel’Thuzad takes over with a new turn when the second phase starts. It is therefore critical to plan for this and do things in the right order during that last turn of phase 1.  Many times it is a good idea to stall phase 1 ending until you can set something up to kill Kel’Thuzad as soon as phase 2 starts.

Once you keep the phase switch in mind, the rest of the fight is really not that difficult.  Due to the fact that you will be frozen for most of the fight weapon cards will not help you therefore don’t bother with any in a deck for this fight.  What you should focus on instead is some control in the form of taunt minions or AOE damage for his minions, and some form of healing so that you can stay in phase 1 as long as it takes to setup your end game.  This means that Priest, Druid, and Paladin decks can all fair well against Kel’Thuzad.

Once you are at the end game part of the fight, remember the fact that Kel’Thuzad will be using your minions against you sometimes.  Therefore make sure you do not bring out a minion that could kill you off if he took control over it.  Also try to make sure that you do not have just a single minion in play at a time or you know which one he will get, unless of course your health is higher than his, then trading back and forth the same damage is just fine.  Another good strategy is when you do have a powerful minion in play, ensure you summon several weak minions as well.  Since the minion he gets is random, the more options there are, the less likely he is to get the good one.

Heroic Mode - When attempting this fight in heroic mode Kel’Thuzad will deal even more damage with his Frost Blast in phase one doing 3 damage per use.  Then in phase two his Chains ability will grant him permanent control over an enemy minion of his choice!  In addition he will summon 2 5/5 minions with taunt at the start of phase 2.


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Last Updated: Mar 13, 2016

About The Author

Byron 1
Byron has been playing and writing about World of Warcraft for the past ten years. He also plays pretty much ever other Blizzard game, currently focusing on Heroes of the Storm and Hearthstone, while still finding time to jump into Diablo III with his son.