I killed a lot of the opponent's Troops but they lost only a little power, why?

If you deploy a Titan to battle, you'll have to keep in mind that the power destroyed by a Titan is not taken into account in the final calculation of the battle result.

As a result, your Titan might kill a lot of your opponent's Troops but you may still end up losing the battle if your own Troops lose more power than the remaining Troops after the Titan deals its damage.