Bag of PAIN

A dyed dark brown, cotton draw string bag, with 20 small sharpened grey 4x2 Legos pieces inside. Setting out the Legos, if a creature of large size or lower fails to notice the Legos, and steps on them, each Lego you step on is 1D4 of piercing damage. The area the Lego's cover is counted as difficult terrain. The Legos only do damage if the creature if the creature touch's the top of the Lego. The Legos can not be stacked on top of each other and deal the entire stacks worth of damage, only the top Lego. The Legos can be lost, along with the bag, but they can be reused unlimitedly, and even used to build with.