I would not play the dragon. What for?
You have two great cards in hand, probably among the best in your deck, that you need to throw away if you play it. All you need is a land to start destroying them. Leap puts cards in hand, but also gets rid of any annoying non-creature cards that might take away your board advantage. Did you know about the rare? Probably not. If you did, you hold the perfect answer to it with
Unholy Hunger. Which also answers a fight card/combat trick, netting you card advantage. He is also not black, so that he can't make you discard the bomb.
In the end, you lost to a two-card combo involving a bomb rare. That is very unlikely, but as you point out, it might have been a common. Dragon is a Johnny card, powerful, seductive, dangerous to both players. Spikes take away a part of the danger by not sacrificing their hand to it.