This is not my idea, but someone in my clans.
After each battle, when it tell you what troops you have expended, it also tell you how much damage that troop has done as a percentage.
For example,
For a gowipe attack it might say:
Golems x2 -15%
Pekkas x3- 40%
Wizards x20 -45%
This would help so that when you attack you would know how effective each troop was, and whether you should include them in your next attack.
Cheers

