That's the situation I was left with in a recent escalating game of mine. It was down to only two of us and whoever had the next set definitely wins, so I just ignored that possibility. I had 4 cards at the start of my turn, so I only needed to survive one more round to win. Obviously, I'd like to reduce my chances of being eliminated without my opponent cashing, but I wasn't sure how to best do it. Do I leave my already outnumbered stacks or do I just attack endlessly into my opponent's stacks? I've included an illustration. I'm pink, and I'll have five cards while cyan has four and a pending deployment of six troops.
