no it'd just be lame sorry..
Skills need a lot more depth, and need to be really cool.
They need to have variaty. (depth)
They need to work for various purposes. (depth)
They need to synergize with both the Demigods own other skills aswell as allies ones. (depth) (currently the rook is the only one with synergies, and he only synergizes with himself and other rooks.)
We don't need.. make a wall. 
IF there was a wall it should be something you use to stop people from running away.. like queen of thorns vine wall, or torchbearer ice wall.
But then you have to give up 1 of TB's ice skills to make a wall. And if you really want rook to make a wall, what are you going to remove?
Hammer Smash? It's freaking cool.
Boulder? Without it Rook will get kited to hell and be useless for everything except destroying buildings and creeps. He has to have SOME Demigod killing power at least! So this synergizes with Hammer Smash.
Tower of light? It synergizes with tele-to-building, the rooks building suck, and the light tower on the rooks shoulder.
Building suck? It's what gives the rook a lot of his base destroying power.
So you want to break the best designed character in the game to give him something dumb like a wall? 
You have to TAKE AWAY his hammer smash and boulder, two skills in the game that work togethe wlel.
Or his tower, which synergizes three different ways, which is more of what this game needs!
OR his building suck, a fundamental skill for the rook.
No it's just a bad idea, sorry.