While Felix's expansion was happening in the Central Continent, William had already left the Elven Capital and headed to the Forbidden Ground of Hyperborea. He knew that time wouldn't wait for anyone, so after tying up some loose ends, he set off without another word.
The journey towards his destination wasn't that troublesome. At least, that was what he originally thought.
However, before he could enter the Forbidden Grounds, he would need to cross the Rhipaean Mountains, where the Guardian of Hyperborea, Boreas, was located.
Only by getting past his trials would someone be able to enter the Land Beyond the North Wind, which was also called the Eternal Garden of Apollon, where an eternal spring could be found.
This was the resting place, and the last hurdle before they finally reached the Forbidden Ground of Hyperborea.