Measuring range for attacks from Walls makes me grumpy.
Consider the following layout, with zones labeled W,X,Y,Z and the wall in red.
[W][X]
|[Y][Z]
You, a mage in zone W, can cast Chain Lightning at the wall, because chain lightning has a range of 0-1, and zone X, which the wall borders, is a distance of 1 zone away. Likewise, a mage in zone Z could cast Chain Lightning and hit the wall because of the distance of zone Y. So... it kinda stands to reason that Chain Lightning can be cast from W at the Wall, and then hit a target in Z on the first hop.
Well, ok, maybe.
Attacking Walls
A creature in either of the zones bordering a wall may make a melee attack against that wall. Ranged attacks may target a wall if either of the adjacent zones is in range, and the wall is in LoS. Walls do not occupy a zone, and are not affected by Zone Attacks or spells that target a zone.
Note that you never actually check that a wall is in range of a ranged attack, only that one of the two adjacent zones is. And there's nothing written about attacks where the wall is the source.
COUNTING DISTANCES
When a creature moves, or when you make an attack, you will need to count distance across the arena. The distance, or “range,” is always counted from one adjacent zone to another (only horizontally and vertically, never diagonally).
Sooo.... range is always counted from one adjacent zone to another. There's no legal way to count range for an attack from a zone border.
Now, this is pretty clearly an oversight, and as far as I know, it only effects one card, Chain Lightning.
Basically, it comes down to this:
Can you hit a wall with a 0-0 ranged attack if you're in an adjacent zone? (Yes.)
Can a wall hit anything other than itself with a 0-0 ranged attack?
The available choices right now are either that 0-0 can't hit anything if it comes from a wall, or that a wall in the center of the long edge of the board is only 1 zone from either of that edge's corners. Neither of these are great options, but for now, for attacks where a wall is the source, I believe the rule is that you have to count as if the first zone is at range 1, if for no other reason than that the wall is not in the target's zone, so can't hit it with a range 0-0 attack.