His principle form of communication seems to be antagonism and he enjoys manipulating people and situations on a level that is perverse and pathological. Employing Machiavellian antics in social interactions for the sole purpose of creating anarchy, ridiculing "the ignorance of others", and couching it in the guise of being a revolutionary or intuitive reformer.
His power manifests in the form of fear/nightmares, an effective living monster weapon, he can transform into any type of reality warping manifestation of fear. So anything you've ever seen in a scary movie... he can turn into that and fight ~as~ the monster itself.
The root of his power is primarily a combination of the emotive and imaginitive planes and in turn the creation of his power was largely influenced by physical reality and the void space. In effect he stared into the infinite abyss... and then decided to become the living embodiment of it.