This Eye Crystal is essentially a spiritual power resource, similar to other precious spiritual power resources.
After Duke consumed it, he digested it, and the Eye directly transformed into a stream of pure spiritual energy, flowing into his mind and began integrating with his spiritual power.
This type of spiritual power resource generally consists of highly pure spiritual energy, making it effortlessly absorbable by any being with spiritual power.
However, these resources usually have limitations; once absorbed to a certain extent, further absorption becomes ineffective, requiring different types of resources.
This Eye Crystal likely shares similar limitations, though the exact number needed for effect remains unknown.
Originating in the Nightmare Plane, Duke has no means of obtaining it in large quantities, so precise data is unattainable.
