The Realm of Hardness, also known as the Hardementium Prism is a pocket dimension that contains the power of Hardness. It was created by Khaz'goroth the titan.

This Realm is the home of Bullingballs, where he spent nearly ten-thousand years of his immortal life. It is here that Khaz'goroth poured his knowledge in to the mind of Bullingballs. Very little is known about the Realm of Hardness and what is known has been told to us by Bullingballs the Hard.

Sometime after the death of Bullingballs, The Realm of Hardness merged with the Realm of Malfurion.