Funny note: it still works, if u want to beat him u can do it easily with this deck, rip naxx, c'ya guys!
Kel'Thuzad, you cheater, my Inner fired minions will destroy you!
Our enemy starts with 45 hp, 20 armor and ability:
Frost Blast - Deal 3 damage to the enemy hero and Freeze it.
He will use it every turn, thats why it's good to be priest, also Lightwell helps a lot.
His deck contain 30 cards, thanks to user Beonitas we have all of them listed here:
2 x Frost Shock
2 x Zombie Chow
2 x Frostbolt
2 x Acolyte of Pain
2 x Dark Cultist
2 x Shadow Bolt
2 x Skeletal Smith
2 x Shadow Madness
2 x Abomination
2 x Frost Elemental
2 x Sludge Belcher
2 x Spectral Knight
1 x Blizzard
2 x Twisting Nether
Probably best target for this combo is [card]Deathlord[/card], he got 8 hp so we can have huge minion, and also he got taunt!
When we deal 20 dmg to Kel'Thuzad and destroy his armor (or in his 11 th turn) he will instantly end our turn, summon two Guardian of Icecrown and change his passive to:
Chains - Take control of a random enemy minion. Cost: 8
So it's nice idea when we're about to destroy his armor to do everything but attacking him and then deal as much damage as possible, to not waste our turn/our minions attack. Also dont leave your buffed minion alone when Kel'Thuzad got 8 mana, it's not the smartest idea ^^
To deal with his taunts we have
Silence(not anymore, but u can use it if u dont have some cards ;) ) and [card]Mass Dispel [/card], buffed and taunted minions with [card]Sunfury Protector[/card] can "passivly" clear his board. When they're dead we can smash his face with our inner fired minions, and probably hopefully ^^ kill him before he will be able to use new passive.
Muligan for Lightwell, [card]Northshire Cleric[/card] and [card]Deathlord[/card], when you got this you want to have also some buffs, always throw away 3+ cards that aren't [card]Deathlord[/card]s. It may take some games, you may need to muligan and surrender several times to get what you need, but its imo best deck for this boss. It's also duel against AI so you can do it again and again, don't need to win 10 times, once is enough, and with this deck you only need to do your combo and dodge Chains/Twisting Nether it IS possible ^^
Also, if you don't want to give him time to steal your minion, you can kill him before he get his second ability, it is not so hard, you just need to have 46+ attack creature... Like this:
Gl Hf and enjoy new card back ;)
My adventure decks:
Dark Iron Arena: http://www.hearthpwn.com/decks/220536-dark-iron-arena-heroic