Stair arms are black hands that come out of the walls
of hallways and staircases, they are obiviasly hostaile
and if they see they will come out of the wall and grab
you, push you to the wall and absorb you.
To check if there is a Stair arm trow a rock in front you
as it will activate them because they funcion like a motion
sensor, and if you are on staires it's better to carry the
rock after you trow it.