Kingdom: Oasis, Urchin*, Feast, Fortress, Tournament, Young Witch, Counterfeit, Harvest, Margrave, Minion, TacticianI waste way too many turns building a fancy double-Tactician engine with Mercenaries trashing Fortresses for economy. My opponent mirrors to some extent, but ends up playing a more money-oriented strategy that gets him a seemingly insurmountable 14-point lead: I need both remaining Provinces and a Duchy for the win, and I need my opponent to not get any more points. With only $8 and 2 buys in my deck, that sounds like quite the challenge.
So I think, and think, and think... and buy...
double tournament.