Substitute. Wild Magic

The "Obsessed with Magic" cycle is a pair of fantastic novels by Roger Zelazny, filled with wonders of technology and magic. Once, the World was one, uniting great cities with powerful machines and magic that every inhabitant possessed. But not everything lasts forever. As a result of a cataclysm, the once whole was divided into the World of machines, our Earth, and the World of magic. Pol, the son of the defeated evil wizard, was sent to Earth as an infant. But as he grew older, his heritage became more apparent. Until the time came to return to his native world, becoming a powerful wizard, defeating numerous enemies, and taking his father's place.