Sounds exciting. I like those design decisions. The stuff about large scale, terrain deformation, world affecting spells, and just general epic wizard battling is a great flavour when done right.
I am thinking of Sourcery (Terry Pratchett), where the wizards all build huge towers and throw magic at each other, with most of it rebounding off and laying waste to the surrounding terrain (it's a far better book than I make it sound).
Or throwing fireballs in Black & White, now that was a joy. Superheating stone for dropping on people's houses, and breaking up that huge pile of rocks in the final level to make an everlasting fire.
And Dominions, a game with a lot of problems which still somehow manages to hook me in. Swarming frost giants with flame-blessed flagellants, sacrificing blood slaves, mermen and kraken fighting undead hoardes at the bottom of the sea. And all the while the mages and priests put on a light show.
Most of all: fortresses in the sky, mana nodes, regenerating death trolls, phantom warriors, war bears, invisible flying warships.