Health can be a bit confusing in Knights and Dragons, because you have one main knight, who is more of a direct representation of you in game, having the most health and the best statistics, but then all your other knights too.
You need to keep a careful eye on the health of all your knights and be patient enough to wait for it to recharge before storming into battle again. You can see the health in the top-left corner of the screen, but again this is just the health of your main character.
Health is regained over time, so there really is no excuse, other than impatience, for rushing in when it's low.
TIP: If you are about to level up, or clear a stage, it can be worthwhile to use low-health knights. If you level up while in combat, all your knights are restored to full health!
You are able to use gems to restore the health of your knights, but normally it is better just to remain patient and wait for their health to recover naturally over time.
Is there any way to upgrade your health
So um how long does it take to get health back?[color=red][/color]