The funny thing is that I didn't even put work into it. He bought like 7 or 8 Ambassadors total, bought 6 or 7 Cities, and just proceeded to load up my deck with as many coppers as possible. He junked up my deck so badly that it made Gardens incredibly valuable. I was still able to buy enough Labs, Cities, and Hunting Parties to keep my deck flow decent, and I bought out most of the Gardens. I still thought I had lost by far, but I won because I got over that 70 threshold.