Eldritch Smash

You crush a tiny creature in the palm of your hand, causing your hands to glow. The next time you hit with an unarmed melee attack, you may choose to inflict 4d12 force damage. A creature of similar size to you is knocked back, or up, that many feet, rounding down to the nearest multiple of 5, and is now prone. Halve the distance knocked back for each size category larger the target is to the caster, and double the distance for each size category smaller the target is. Colossal creatures cannot be moved or made prone in this way. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d12 for each slot level above 3rd.