Wizards is Taking Place in The Same Dimension as Felix the Cat: The MovieThink about it. You have the dimension of Oriana that has ancient lost technology, hideous reptilian mutants and a fairy princess with magical tears. That sounds like a description of the Earth of Wizards. It could be taking place in some other part of this planet.
Wizards takes place in the same universe as Adventure TimeBoth take place on Earth, long after a nuclear war which resulted in magic returning to the world. They also both have a huge range of bizarre creatures and a mishmash of magic and technology. Perhaps the Ice King is Avatar and Blackwolf's other brother.