Soul Prism

It is a semi-rare drop (1 to 5% chance of drop) from fiendish creatures.

Can be used on a Soul Core to transform it into the Soul Core of a random creature from the next higher Bestiary difficulty level. If used on a Soul Core of the highest bestiary difficulty, it will just transform it into a random Soul Core of the same difficulty. In rare cases the Soul Core will not be consumed, and the player will receive an Ominous Soul Core instead.