Is the Miracle Cube package worth it?

I'm so confused. I just wanted to get the best damage for the least amount of cost. I'm really only willing to buy cubes just during events. This is like my first time trying out cubes. I just wanted to go with Ring first since I don't even have a Unique weapon (which is the only way to unlock Boss dmg).

Also, what exactly do you mean by primary stats from a cube? Mind giving an example maybe?