Not only 1 card available, all 10? Then, probably Chapel down, building a big Goons turn (or KC-bridge?) and possibly Quarry for a quick Goons?
also, beware of the pin...
EDIT: Yes, Ambassador over Chapel, of course
Yeah, I'd also be looking for a Goons deck. I'm wondering whether I want Labs, Stables, or Minions though. Minions work well with all the cheap disappearing actions you can get(Fishing village, Hamlet, Lighthouse, etc...). Then again, an Ironworks/Silk Road rush would be nuts. Maybe heavy Bishop can do something about that? Another opening to consider is Chapel/Ironworks, but I'm not sure what the optimal strategy is with that opening.
You know what becomes a power card in this setup? Develop. Okay, so it's forced to get Poor Houses if you trash $0 costs or $2 costs, but it's beastly at the higher price points. Band of Misfits is nuts too.