I am having problems figuring out what fields are covered by ranged attacks, and which fields are not. The coverage continues in a straight line, but then spreads out covering more fields. How do you know which field is covered and which field is not? I rely on my intuition, but it is not working very well. Can someone point me to some rules? See the attached image. Why are the red-outlined squares blocked, but the green-outlined not?
From the very middle of the position of your wizard, the middle of the green fields can be seen (barely), while the middle of the red fields cannot. Just try to draw a line between them, one will collide with the blocked terrain while the other won't.
More precisely: to determine Line-of-Sight (LOS), draw a straight line from the center of one square to the center of the other. If that line crosses blocked terrain, there is no LOS. (This can be hard to work out in practice, though...)
Note that Linear spells work a little differently: the target has to be in LoS, but it will affect every square that line intersects, even squares that aren't in LoS themselves.
