Magic Stone as written is crazy strong. As noted, it can't scale, because you can get allies to throw it for you (or you can, with Extra Attack).
A level 6 artificer can have extra attack. They can now throw 2 pebbles, doing 2d6+int+int damage. This is scaling; if you had 2d6 damage pebbles, it would hyper-scale.
By level 11 they can cast Tiny Servant. Use one bonus action to make the pebbles before the fight. In combat, as a bonus action get the Tiny Servant to throw it, plus your action, for 3d6+int*3 damage (~25).
By level 15 you can cast 4th level Tiny Servant, creating 3 Servants. Before combat make 3 pebbles. In combat, as a bonus action have all 3 be thrown, for 3d6+int*3 damage as a bonus action (~25). Over 2 bonus actions you can repeat this in combat, doing ~13 damage per bonus action.
Said servants can also use your 10 charge spell storing item.
Not all Artificers get an extra attack at 6, however. But about half of them do.
