Number of troops killed in a battle
At the end of a battle, it always shows what troops you used, how many, how much loot you got, how many trophies you won, etc... I think there should also be a red number next to the pictures of the troops used, that shows how many were actually killed by enemy defenses, bombs, and clan castle contents. This could also be shown on your defensive battles as well. That way you know how exactly how well your base is working without watching the replay. Even with the replay, its hard to tell exactly how many troops you managed to take out.