Is there a specific rule whereby Wall's cannot have attack/can attack? Because placing a orc cheiftain next to a wall does not give it the 2 attack bonus nor the ability to attack. Clearly list if the wall can attack please.
Tactic: Buy lich asap, get as much command as possible, keep summoning lich, buy giant skeleton summoning spell as well as normal skeleton warrior spell, add to your list because they add extra command + 1 to your army. Keep summoning lich. You'll have a small army of skeletons.
If it were possible to upgrade your base's hp, although at a high cost and very limit upgrades to make it fair. Maybe add a few more world's as challenges? One's that make the last level look easy.
Yes wall is not meant to attack