I'm looking for some fun drills to do with my 12-year-old son (intermediate level). We play a game called "murder" where one person is "king," and you play a groundstroke rally (and if the opponent wins), a volley rally, then overheads, and if he wins them all, he becomes king. But I was looking for other drills/games to make things more interesting. We usually just baseline rally, and rally only in the service court, but that gets stale after awhile, so need some fresh ideas. Thanks.