Astral Caltrops

As an action, you can spread these magic caltrops over a square area that is 5 feet on a side. Any creature that enters the area must succeed on a DC 15 Dexterity saving throw or stop moving this turn and take 1 piercing damage. When this happens, the caltrops explode in a burst of extraplanar energy, destroying the caltrops and dealing 6d6 force damage to the creature and causing it to rise vertically up to 20 feet, as if by the levitate spell. The creature remains suspended in this way for 1d4 rounds, during which time its speed becomes 0. The effect ends early if the creature takes any damage.

When the caltrops are spread on the ground, they become nearly invisible and float up to 1 inch off the ground. A creature notices the caltrops with a successful DC 20 Wisdom (Perception) check. You can reclaim the invisible caltrops for later use with 1 minute of careful searching and collecting. The caltrops stop floating and become visible once they're reclaimed in this way