I read in the FAQ that we can't make breath attack trought staircase!

But can we make a ranged or a magic attack trought it?

I know you can attack trough it...but I don't remember if you can only attack adjenct to the staircase on the otherside...or draw los from it aswell

JitD rules page 17:

"Attacks may be made through a staircase just as if the two staircase spaces were adjacent. A figure standing on one end of a staircase has line of sight to the other end of the staircase and its adjacent spaces, while a figure standing adjacent to one end of a staircase has line of sight to the other end of the staircase."

Thanks!