Darnak's Graviton Cannon

You launch a fist sized orb of solid material at a target, which can be prepared ahead of time, or as part of the casting you gather material near you into an orb. The projectile is spun in place and then launched at incredible speeds at the target.

Make a spell attack roll against the target. On a hit, the target takes 8d8 bludgeoning damage and is moved 30 feet away from you. On a miss, the target and all creatures within 15 ft must make a Dexterity saving throw or take 4d6 piercing damage and 4d6 force damage and are pushed 20 ft from the targeted creature's space. On a successful save, the creatures take half damage and are only pushed 10ft. 

Large and smaller creatures are pushed the full distance by this spell. Huge creatures are push half the distance. Anything larger than huge is not moved but sill takes full damage. 

Specific materials used for the projectile can be reused if recovered as the spell hardens the material used for the projectile. Roll a d20 on impact, anything 10 or higher and it does not shatter. If the roll is lower than 10, it shatters, and on a shatter increases piercing damage by 2d6 on a miss and adds 2d6 piercing in a 10 ft radius on a hit.:

• Steel or iron spheres can reused indefinitely.
• Granite spheres have a chance to shatter on impact. 
• Hardwood spheres have a high chance to shatter, the shatter chance increases by 5.
• Softwood spheres always shatter, the added damage is only 1d6
• Spheres made of glass, ice, or those made in the casting of this spell always shatter and cause no extra damage. 

At higher levels. When you cast this spell using a spell slot of 6th level or higher, the damage increases by 1d8 and 1d6 force or piercing damage for each slot level above 5th, the distance a creature is pushed increases by 5ft for every spell level above 5th, and the radius of a missed spell increases by 5 ft for every spell level above 5th.