This deck helped me beat Heroic Lord Slitherspear on the second try. The main goal of the deck is to use Animated Armor and your freezing cards such as Ice Lance, Frost Nova, and other cards to stall out Lord Slitherspear until you can either kill him with minion damage or get the cheese strat out.
What is the cheese strat, you ask? Playing Kel'Thuzad with Annoy-o-Tron or Mirror Image. The Blizzard AI will not attack a taunt if there is a Kel'Thuzad behind it, so you are pretty much safe to hit his face.
Animated Armor is your best stalling method. Other decklists online only include Animated Armor minions in hopes of your minions being able to deal all the damage, but if that doesn't happen, you have an alt win con which is your cheese strat.
You can still win with stalling and minions because I added in an Arcane Golem for burst, because I often found myself missing 2-3 damage and that ended up causing me to lose the game.
If you find that this isn't enough stalling, then you can tech in a Blizzard.
Once you get Animated Armor out, ALWAYS attack his face with it, you need to kill him ASAP. He will usually deal around 7-8 damage per turn to you, so you will want to play Antique Healbot and Ice Barrier ONLY AFTER you play your armor, as they will buy you one turn each. Frost Nova's can be used more liberally, but you should try to use them to buy you extra turns once you already have the armor up.
The AI should never attack your Animated Armor with his Nagas, but be warned that he will start killing Animated Armor's once you get him down into lethal range, so try not to get too low that he can kill you on the turn that he trades with the Animated Armors. Good luck!