[Illuminated One]

@HoneyBadger

Ok, for some mages it might be ok if they did some digging, but then again for most mages I can't see why anyone would want to waste a mage +gems for something a bunch of soldiers with picks and shovels could do as well.
There are possibilities to couter elephants with magic allready (Bonds of Fire, Paralyze). Well I don't know how powerful these are in a real game but then I think it sucks to be forced to use your mages to counter something that could be easily countered by mundane means.
However it occured to me that you could also give some infantry commanders (say ulm's siege engineer) the ability to domsummon barricades which would indeed make sense imo.

Still I don't think it would work very vell in battles as long as units can't differentiate between enemies and obstacles. And while a wooden pallisade torn down by elephants makes sense a couple of spearmen stabbing the palisade to death while under enemy fire does not.