abyssaldeath
First Post
Exception to this is the wizard power, Phantasmal Terrain (Utility2), which makes difficult terrain more difficult (2 squares to 3).
That's not an exception because Phantasmal Terrain doesn't create any terrain at all. It augments terrain so it is not a case of stacking terrain. It is potentially a very potent spell though.
Difficult terrain + Phantasmal Terrain + a slowed enemy = an effectively immobilized enemy while he is in that terrain.