Arcane Lens

You cast out a spherical lens of arcane force that hovers in the air at a point you can see within range.
If, before the end of your next turn, a spell is cast that passes through the square the lens inhabits on the way to it's target, roll 1d3 and multiply the spell's damage by the result. On a 1, add the lens' spell level to the damage. After the Arcane lens is used once, it dissipates. This spell is only capable of empowering a spell of its own level or lower, or a cantrip.