Your favorite unit...

It's better to just hit them with a fireball than to do all this complicated stuff, although the wall is a good thing...

You're right, it's best to cast the Fire Sign at level 6 before that, and it's even better...
Regarding the combination of walls with bears and harpooners... No normal player will leave the wall in such a way that it would be possible to return them there with bears or harpooners... And bears sometimes push in the wrong direction, you run to block archers, and they push them straight into the archers' line of fire((