THIS IS NOT A GOOD OR COMPETITIVE DECK.  It's only for purpose of the combo challenge below.  If you're bored with ladder, see if you can make a better one!  Best of luck!

The goal is to win a game with a 100% guaranteed Holy Wrath > Molten Giant for 25 damage.  In order to pull it off:
1. You must have one card left in your deck, and it MUST be a minion
2. You must have 5 or less health (or close if you have additional discounts from Emperor---see below)
3. Your opponent must be at 25 health or less
4. You must have had Emperor Thaurissan hit at least once on Holy Wrath or Madam Goya

If all the above conditions are met, you play your Molten Giant, which should cost zero, use Madam Goya to swap it as the remaining card in your deck, and then Holy Wrath for the win.

It is really hard to pull of for several reasons:  If Emperor Thaurissan or Madam Goya is the last card in your deck, it cannot be done.  If the last card in your deck is not a minion, it cannot be done (you can have a 50/50 shot with two cards left if one is a minion, but not the point of the challenge).  Thus, when crafting a deck to meet the challenge, you'll want to have as few spells as possible (if any) other than Holy Wrath.  You also need be very precise in keeping your health at the right level.  I've had several games where I drew out my deck before I could get the giant down.

Good luck!