Well having the enemy pass would be the easiest solution. This game does not take as long as a hearthstone, and you have only 1 play to make each round, so timing out should be less of an issue.
Playing random cards, can also mean you can just go afk and let the game play for you, which is something I do not want to have, especially since the enemy always has to wait the maximal time per round (which of course could go faster the second round like in hearthstone, but still it would be annoying).