A ball of snow forms 5 feet away from you and rolls in the direction you point at a speed of 30 feet, growing larger as it moves. To roll the boulder into a creature, you must make a successful ranged spell attack. If the boulder hits, the creature must make a successful Dexterity saving throw or be knocked prone and take the damage indicated below. Hitting a creature doesn’t stop the snow boulder’s movement or impede its growth, as long as you continue to maintain concentration on the effect. When the spell ends, the boulder stops moving.
 

Round	Size	Damage
1	Small	1d6 bludgeoning
2	Medium	2d6 bludgeoning
3	Large	4d6 bludgeoning
4	Huge	6d6 bludgeoning