The Goofball. Attunement. When you speak the command word this ball bearing flies and lands at a point within 30 feet of you and expands into a large sphere. The sphere is made up of differently textured panels. On your turn you can use a bonus action to direct the Goof Ball to move up to 30 feet. When the Goof Ball collides with a creature or a creature starts its turn within 5 feet of the Goof Ball the target must make a DC15 Dex saving throw. If they fail roll 1d6 to determine which type of panel the creature is struck by.
1d6
1: Spikes, the target takes 6d6 piercing damage
2: Rubber, the target takes 2d6 bludgeoning damage and is pushed 15 feet away from the Goof Ball
3: Thorns, the target takes 2d6 piercing damage, 2d6 poison damage and must make a DC 15 Con save or be poisoned for 1 minute
4: Goo, the target must make a DC 15 Dex save or become restrained and be attached to the Goof Ball
5: Ice, the target takes 4d6 cold damage and has their speed reduced by 10 until the end of your next turn
6: Roll again twice ignoring this result if it comes up again
After 10 minutes the Goof Ball returns to its ball bearing form and returns to you. If the Goof Ball is more than 100 feet away from you in reverts.
I'm not sure how powerful you want it to be, but you can adjust the numbers as you see fit. You could also add more options if you're more creative than I.