In Black Plume Mountain, I put up an Illusionary Barrier to try and stop some of his breath attacks. That worked... kind of. He could still hit me with a breath attack if he tried to breathe on me, only now I had no way to tell if I was in his LoS, because if I clicked on him it looked like he was blocked by the wall - I couldn't tell the difference between that and the stone blockers. In Oozeball my opponent put up a barrier, and if I clicked on his Ooze I could see what he could see, but I couldn't tell what I would have line of sight to. I tried "ctrl-click" on a square to identify the LOS, but it shows me the LOS as if the wall was blocking. In the oozeball example that would work - but it would help with the dragon example. It would be nice if I could tell the difference between "blocked one way" and "blocked both ways". Either it could be 3-state e.g. (red means enemy sees, blue means I see, purple means we both see, or using cross hatching that alternates), or 2-state (green means visible, green with crosshatching means visible to some people)
Cone attacks (Breaths) don't require LoS. You simply pick a direction and in-range squares are affected. Illusionary Walls, Smoke and similar effects only hinder LoS, not the effect from taking place. This is also why, for instance, you can Cone of Cold people sitting in/behind a cloud of smoke, but you can't Flame Jet people, as it needs LoS for picking a target square (this is slightly untrue, as you can target squares you have no LoS-to when directioning the spell at weird angles). Regular walls (both the normal ones and Wall of Stone), on the contrary, do block effects. You can use a solid wall to take shelter from an enemy breath attack, but you can't do the same with an illusionary wall or smoke.
This is because Flame Jet is a linear attack. Linear attacks will effect characters of any square through which line of sight travels when drawn from the center of the caster's square to the center of the target square. This includes squares that may only have a corner of the square crossed by LoS and could not be targeted directly as LoS to the center of the particular square is blocked. Thus it would be better to say you can effect squares you have no LoS to (just as you can with cone attacks) but you still cannot target squares to which you have no LoS.
I know - that's why I wanted this. I couldn't tell the difference between places the dragon could use Blizzard_Breath and when he could use Ice_Bolts. Without the illusionary wall those squares are the same. With the illusionary wall there's a difference. In theory my suggestion is still inadequate, if I have an illusionary wall up and my opponent has an illusionary wall up and both are in between us then my view would look blocked even with my suggestion even though a cone of cold could get through. So maybe it should disply a difference between "blocked for targetting" and "blocked for cone effects".
Sounds like the core matter is to introduce a additional paled out version of the enemy units view when you hover over it with the mouse. One that indicates the squares he has access to with said attacks, even though he can't see because there is smoke or illusion. Or expressed differently, everything he could see if there werent those obstacles.
