Thorned Tumbleweed

You summon a thorned, tangled plant somewhere on the ground within five feet of you. Immediately after casting the spell, you can command the tumbleweed to move up to 30 feet or until it hits a creature or object. Any creature or object touching the tumbleweed when it stops moving must make a Dexterity saving throw, taking 3d8 piercing damage on a failed save or half as much on a successful one.  As a bonus action on your turn within the spell's duration, you can command the tumbleweed to move up to 30 feet again. The tumbleweed can occupy the same space as any creature or object and cannot be damaged. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, summon an additional tumbleweed for each slot level above 2nd.