I have seen a thread that wanted lvl 12 walls to have canons in them. I agree with that idea but here are some condition to make them work:
First, they can hit wall breakers or they are too hard to destroy
2nd: they can only shoot in front of them. They are not like normal canons that can turn and shoot in different dirrections.
3rd: Damage per sec would be 3-5 because normal canons are already strong enough to defend
4th: their favorite targets are giants

