Ball Bearings (bag of 1,000)

As an action, you can spill these tiny metal balls
from their pouch to cover a level, square area
that is 10 feet on a side. A creature moving
across the covered area must succeed on a DC 10
Dexterity saving throw or fall prone. A creature
moving through the area at half speed doesn't
need to make the save.
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Cost 1 gp Weight 2 lbs