Life bar would be good. :} Or point bar in this case. But, I always imagined it should work like this:

You hit, you get points that fills the bar, then a countdown starts before there will be possible to fill the bar again. As the turns starts to get closer to a match finish the countdowns are getting shorter. Too passive and you can't score, can't make your point bar larger, too active and you could miss to fill your bar better, with more points. You need to find balance and have good timing, and since the game has a timer with turns it could easily turn into strategy fight of attacks and faints. :]