Alrighty we ran into this in our game today,
basically the hero wanted to target a tree for blast to hit a beastman next to the tree (whom she did not have LOS) and not hit herself
So the question is : Do you have LOS to the square that blocks LOS?
In the rules it says:
Line of sight is blocked by walls, closed doors, other figures,
and blocking obstacles. Thus you cannot, for
instance, shoot directly through one monster to hit another
monster behind it.
However you can taget a monster (which blocks line of sight)
The other thing in the rules is the diagram of LOS: the rubble is not highlighted as to say you can't target it but the monsters are
Hopefully there is a ruling on this I just missed , my gut says you can't but who knows when it comes to descent
Thanks, Greg