Hearthpwn

My buff deck below. A walk in the park, after you mulligan for the right starting hand.

Kel'Thuzad Buff Priest Silence Priest Deck by zeremwind - Nov 11, 2017 View Deck String Export to BBCode Export to Cockatrice Export to MarkDown Export to Html Clone this deck
Minion (19) 1x Emperor Thaurissan 2x Deathlord 2x Lightwell 2x Bonemare 2x Dragonhawk Rider 2x Gurubashi Berserker 2x Holy Champion 2x Kvaldir Raider 2x Mukla's Champion 2x Northshire Cleric	Ability (11) 1x Mass Dispel 2x Circle of Healing 2x Inner Fire 2x Binding Heal 2x Divine Spirit 2x Power Word: Shield
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After struggling to get the Priest decks to work properly, I cleared him first-try with standard murloc paladin. 

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Minion (24) 1x Bolvar, Fireblood 1x Finja, the Flying Star 1x Sunkeeper Tarim 1x Tirion Fordring 1x Wickerflame Burnbristle 2x Gentle Megasaur 2x Murloc Warleader 2x Vilefin Inquisitor 2x Murloc Tidecaller 2x Stonehill Defender 1x Spellbreaker 2x Bonemare 2x Hydrologist 2x Righteous Protector 2x Rockpool Hunter	Ability (4) 2x Spikeridged Steed 2x Blessing of Kings	Weapon (2) 2x Rallying Blade

Establish the murloc synergies early (mulligan for tidecaller or inquistor), and you should be able to drop his shield without too much trouble. Tarim is amazing when he floods the board, and you can weapon down anything that escapes your minions. In phase 2, he seems to love to take control of your 1-1 dudes, but if you land a bonemare on wickerflame, it can heal you to full. 

It's all about race... keep racing and you will win. Thanks for the deck :)

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Minion (16) 1x Lyra the Sunshard 2x Deathlord 1x Injured Blademaster 2x Lightwell 2x Wild Pyromancer 2x Kabal Talonpriest 2x Northshire Cleric 2x Priest of the Feast 2x Radiant Elemental	Ability (14) 2x Shadow Visions 1x Light of the Naaru 1x Mass Dispel 2x Circle of Healing 2x Inner Fire 2x Divine Spirit 2x Power Word: Shield 2x Shadow Word: Pain

Priest of the Feast definitely mvp of the deck. You could probably switch out Injured Blademaster and Mass Dispel for Shadow Word: Death.

Tried to use the Priest decks but never getting three cards in time to make the combo.

Used a Shaman deck I found in the comments and it worked. I made some minor modifications but it worked

Totem Shaman - Heroic Kel'Thuzad Midrange Shaman Deck by setatakahashi - Aug 21, 2016 View Deck String Export to BBCode Export to Cockatrice Export to MarkDown Export to Html Clone this deck
Minion (18) 1x Draenei Totemcarver 2x Mana Tide Totem 2x Thunder Bluff Valiant 2x Vitality Totem 2x Fire Elemental 2x Flametongue Totem 1x Flamewreathed Faceless 2x Piloted Shredder 2x Totem Golem 2x Tuskarr Totemic	Ability (12) 2x Healing Wave 1x Lightning Storm 1x Earth Shock 1x Bloodlust 1x Crackle 2x Hex 2x Rockbiter Weapon 2x Totemic Might
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Ragnaros, Lightlord gg.

Seconding Secret Paladin for this fight.

This deck worked for me and was satisfying.  I forgot where I found it on the web, but decided to post it here.  Best of luck getting that cardback!

Kel'Thuzad Heroic Deck /w Rag Kill Trick Unknown Deck by checkm_8 - Jan 30, 2016 View Deck String Export to BBCode Export to Cockatrice Export to MarkDown Export to Html Clone this deck
Minion (11) 1x Majordomo Executus 2x Lightwell 2x Sludge Belcher 2x Northshire Cleric 2x Piloted Shredder 2x Zombie Chow	Ability (19) 1x Lightbomb 2x Light of the Naaru 2x Resurrect 2x Shadow Madness 1x Inner Fire 2x Silence 2x Thoughtsteal 2x Mind Blast 1x Shadow Word: Death 1x Mind Vision 2x Power Word: Shield 1x Shadow Word: Pain
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Thanks! I won on my second try :D

Thank you for getting me that cardback!

16 card heroic deck? fluxfashor blew it with this guide!

I used the deck shown in the video Windy Priest, took me 4 attempts and then beat him on turn 6. A 20/20 Deathlord on turn 4 is nice. Thanks for the guide.

I did it with generic midrange paladin. Pretty easy to skip 1st phase fast enough and then his hero power sucks versus your infinite recruits.

I´ve suffered trying with Priest... then, in my first attempt to rush with shaman, boom, easy.

Using Healing Touch to keep healed and flood board + totens to break his armor till turn 7 (to avoid a bad luck Twisting Nether), its safe win... he will only steal a minion and won´t have mana to fill the board.

The sequence Dr boom -> Kel Thuzad worked fine.

I beat Kel' Thuzad today using a type of budget priest deck, with techs in it. The whole point of the deck was to keep board control and get a huge minion (I got a 12/12 Stoneskin Gargoyle on T4) until you got to phase 2, where you play Majordomo Executus, he uses chains, then you finish the combo with Shadow Word: Death, and 2 Mindblast. 

I actually didn't end up doing the combo, but he used Twisting Nether while he was out on my side, and I became Ragnaros. Top Decked every necessary card to deal with threats and win the game at that point. Got lucky with hero power targeting a Spectral Knight, using SW:P and D on a Frost Elemental and Zombie Chow as soon as he sent them out, Top decked Silence when he played Belcher... won the turn afterwards.

Oh, now that's a clever use of Executus. Possibly the single cleverest trick I've ever heard of in all of Hearthstone.

Lying pig

he has 2 Twisting Nether :/

Here is our video using Vernitrax's deck, enjoy!