In Edain Mod the Wall Building for the AI is disabled.
In my opinion, the AI use the spell book. The Easy AI never use spell book, but the brutal AI normally use spell book.
So how to make AI build wall or use spell book ?
You have to open your
Return of the Witchking folder and copy the file
____edain_maps.big in an other folder. There you open the file
____edain_maps.big with the programm
Final Big. Than you extract the
data\ini\default\skirmishaidata.ini. Than you open the "skirmishaidata.ini" and change this:
DisableWallBuilding = Yes
to
DisableWallBuilding = No
and save this
After that you add the "skirmishaidata.ini" in your
____edain_maps.big with the name
data\ini\default\skirmishaidata.ini.
You copy your
____edain_maps.big in the
Return of the Witchking folder and replace there the current
____edain_maps.big.