[quote=@Bishop]
[@Meta] Hmm, well I'll go to my back up power theory explanation plan. He has a pocket dimension which is connected to every other dimension and universe. His powers come from this dimension. Dimension of [b]Darkness[/b]... That is a higher dimension so theoretically he is able to connect to any lower dimension as for say, the 3D one.
[/quote]

Pocket dimension is doable as well as higher spacial dimension (we have experience with those as well), but he'd theoretically need to take that pocket dimension with him since Existence is a very large physical place that is intentionally segmented and isolated. So if he wanted to, it could coexist with every dimension, but just not all at the same time.