These magical caltrops come in groups of 1d6+6 and you can use an action to throw any number of these caltrops in an unoccupied 5-foot square on the ground that you can see within 15 feet of you. When you do, roll a number of d4s equal to the number of caltrops thrown and record the total. When a creature steps into that space, it must immediately must make a DC 13 Dexterity saving throw. The caltrops then explode, and that creature takes an amount of poison damage equal to the total rolled on the d4s on a failed save, or half as much poison damage on a successful one. Once a caltrop has dealt this poison damage, it becomes a nonmagical caltrop. The poison gas takes 1d4 turns to dissipate where as the creature or creatures affected take 1d4 damage on each turn.