Ball Bearings of Trapping

A seemingly innocuous bag of ball bearings. When dumped onto a flat surface, enough bearings to perfectly cover the surface spread out. need to make a DC 25 dex saving throw to not fall prone. need to make a DC 18 acrobatics check to get up from prone while in an area effected by the bearings. Placing a single ball back into the bag completely refills the bag and any balls left outside the bag disappear.