Imbued arrow worked for me too... both area and single damage spells. Well when you use it with an area damage spell you must target an enemy stack instead any square (seems logic to me) and iirc the damage area was not highlighted before casting like the normal one (not so logic)
I'm not really seeing any difference at this point from H3. I've just finished playing 2 multiplayer maps [no scripting] against the AI and in neither game [total of 10 AI opponnents] have I seen any hero cast a spell above level 3 and haven't seen a single "mass" spell yet. I was hoping ...