You instantaneously conjure a cluster of thin, magically reinforced iron pillars capable of supporting any type of ceiling in the event of a cave-in or collapse; in addition; it stops traps such as deadfalls and crushing ceilings and floors (but not walls). Creatures and objects within the spell's area of effect suffer no damage from falling debris or crushing rooms while adjacent spaces outside of this area still experience the cave-in, collapse, or trap's full effects. Creatures protected by the spell must still find a way out by digging through the surrounding rubble or via other means.

Support beam only provides protection against cave-ins, falling objects, collapsing natural or magical ceilings; it grants no special benefits against flying or falling creatures. When the spell's duration expires, the ceiling collapses raining debris on any creatures or objects still within its area of effect.