Hearthpwn

Shadow Word: Pain is a key card, and you ought to draw at least one in your starting hand - that's what everyone knows for himself. Now lets see what we can do from here.

Baron Rivendare runs only paladin secrets (Repentance, Redemption and Avenge), spell removals and Runeblade, which has 2 attack with other horsemen alive and 8 attack when other are dead (not necessarily "under opponent's control", huh).

So what are we looking for, besides Pain? Firstly, strong stable minions with 4 attack (due to Baron running priest removals) or immune to spells, like Spectral Knight, which has both these benefits. Some more removal options. Some late-game options via taunt-up and support cards. Acidic Swamp Ooze, of course.

Paladin secrets are a bit of an obstacle, so I included Silence coins here to counter Avenge, which is far better than carrying Shadow Word: Death around. Redemption doesn't do much, so I didn't bother with Elven Archers, but it's an option.

Loatheb does wonders and makes poor Baron sometimes even send all his comrades into him, which makes our creeper "do 5 damage to all enemies for 5 mana" card. Cabal Shadow Priest is added for a bit of a flavor: imagine two SW:Pains, stalling till turn 6, and playing her at the last horseman. Bam, you're immune, Baron Rivendare is not, and his sword is not buffed. Classic.

If you have any questions/suggestions/angry reviews, please, write them down in the comments. GLHF!