Marble of Slipping

Once per long rest, this tiny, unassuming glass ball becomes a thousand marbles for just 6 seconds. As an action, you can toss the marble up to 30 ft and shout its activation phrase ("slippity boppity boom"). Upon impact with the ground, the marble creates difficult terrain in a 15 ft radius for 1 turn of combat. Any creature entering the area of effect or starting its turn there must succeed on a DC 18 Dexterity saving throw or fall prone, taking 1d8 bludgeoning damage on a failed save. At the start of y