Hearthpwn

The key to beating Chromaggus is not to get severely overrun by turn 5 and at the same time, discarding those annoying affliction. Although random, Warlock have the helps of these cards discarding minions and spell to help out in discarding the affliction cheaply. Mulligan for either Zombie Chow or Soulfire

I did not put Flame Imp because I really don't want to take any further damage to my own face. This is going to be a long battle and I want the health to be as high as possible. Same goes for life tapping. Avoid using it since your hand is going to be full of those affliction cards. Emperor Thaurissan is a great card here because you really need a mana discount on those afflictions in the later stage of the game.

Chromaggus does not have a strong removal spell but do take note that he have 2 Flamestrike. The most annoying minion that Chromaggus have is the Chromatic Dragonkin. This minion can be a real pain when you are stuck with dangerous affliction card and you have an open board.

Apparently, Chromaggus seems to give you green at turn 1 and red at turn 2.

Affliction discard priority (5 being the less important and 1 being the most):

Red (Priority 4): Although 3 damage at the start of the turn is annoying, you should just swallow the damage and start out with board control. His minions is more dangerous then the measly 3 damage at the start of the turn.

Green (Priority 5): This should only be discarded when you are about to deal damage to Chromaggus himself. Remember, the match is about control of the board.

Blue (Priority 4 with an open board, 1 when your board is full): I don't see this card to be as dangerous as some player might think it is. Other than Flamestrike and Swipe Chromaggus himself don't have a lot of spell to do damage to you.

Bronze (Priority 1, 3 if you have a strong board clear, 5 if he has no hand): As I have said, his minions are more dangerous than his spells. Discarding Affliction Bronze is always the priority if he has a full hand.

Black (Priority 1, don't bother discarding if he's in fatigue): The last thing you want to see from Chromaggus is another Alexstraza. This deck does not have a lot of answers to his big minions.

I do manage to clear Chromaggus with one try with this. Despite the weak discard start from Soulfire and succubus.