I was thinking maybe you could spice up the gameplay in that level with two paladins fighting through guards to get to the magician. You could add some puzzles to solve in order to pass on, since it's kind of like a tower/dungeon of a wizard. Fighting should be interesting. That requires a multitude of units, diverse ones in which different strategies are required to beat them like with that Crusader unit.
You could make use of doodads/destructibles, some interaction, danger zones, traps, something to give the level more flavour. You could also have some places be less purple. Would help the eyes rest a bit and give them some different food.