Wishful Thinking — Stephanie Bedwell-Grime

The long, magical wars ended when the elves left the lands of men, conjuring an impenetrable barrier to keep the humans out of their new realm. They left man only with the sorcery he could create, taking all the creatures of magic to Ishan with them... except for one...
Aubreyan is the first of an eight-book fantasy series that will take the two heroes to other realities in pursuit of an evil the gods have enjoined them to contain and destroy before the gods and demons themselves are forced to battle.