Hearthpwn

For those people who finished their Level 10 Mage and purchased Naxxaramus, but haven't much by way of Classic Packs. Basically, the notion here is to use spread damage in the form of Arcane Missiles, Arcane Explosion, and Flamestrike to repeatedly wipe the enemy board while landing a few sticky minions that will slow down his offense. Eventually, your goal is to sit pretty behind a taunt-wall of Sen'jin Shieldmastas and Sludge Belchers made immortal by Kel'Thuzad, and gather up some direct damage (Frostbolt and Fireball to finish him off. 

Don't fear dropping a turn-2 Kobold Geomancer against anything but a Priest. Even if they drop a 2/3, you can finish it off with your Hero Power and keep moving forward; if they drop a 3/2, you can often snag it easily with a buffed Arcane Missiles without breaking a sweat. (Priests will just heal up the damage your Geomancer does to his minion and keep swinging, so save it unless his board is empty.)

Your obvious finisher is Boulderfist Ogre, but just as important is Shade of Naxxramas. It's important to know what your foe's biggest nuke is, and don't reveal your Shade if they could easily kill it with that nuke and a minor on-board minion. (Mage: Fireball, Druid: Starfire, Hunter: Explosive Shot, Paladin: Avenging Wrath (needs math to calculate rough damage potential), Warrior: Gorehowl (close enough to a nuke), Warlock: Shadow Bolt, Priest: Holy Fire, Rogue: Assassin's Blade + Deadly Poison, Shaman: Crackle.)  If your Shade of Naxxramas eats a kill-spell like Hex or Crush, so be it, but there's no reason to lose it to a nuke unless you need the threat it provides in order to put your opponent on a short clock and race him down.