Hearthpwn

This deck is all about creating a stable endgame state. You can't afford to let Geddon's hero power go off more than once or twice, and you basically never want to let a Living Bomb explode. 

Luckily, you have lots of tools to make that happen. 

The core of the deck is the pandaren bartenders, the Youthful Brewmaster and Ancient Brewmaster. If you have any two brewmasters, you can use up 100% of your mana on any given turn, as long as you always keep at least one in your hand. Just bounce the brewmasters back and forth until you've spent all you want to spend.

The 2x Duplicate and 2x Echo of Medivh are there to help get more brewmasters into your hand, and help copy your life-gaining minions. 

Brewmasters are a great solution to Living Bomb, but just in case you're not holding one, the Ironbeak Owl, Recombobulator, or (in emergencies) Frostbolt will get you out of the jam.

Hard mulligan for Clockwork Gnome and Zombie Chow to make sure you don't get slammed on your first turn. Spare parts are a great way to spend that last point of mana on turns when you can't quite do it.

Trade intelligently with his minions. You can ping Core Hound with your hero power, but the rest of them will need to be taken down. You might consider trying to fit in some Polymorph, Fireball, or AoE, but I got through without any of those.

The game will almost certainly go to Fatigue, and Jeeves is your friend there: be happy if Geddon is drawing extra cards off him.

Also, keep in mind that since you're not using Alexstraza, the last two cards in his hand are always going to be 2x Magma Giant — he can't cast them until you've done over 60 damage. Be ready to deal with them once you've worn his armor down.  

If you can keep the Ice Block up, and pair it with an Illuminator or two, you'll outlast him, especially if you've got an Ancient Healbot to bounce and replay as well.

Good luck!