Empyrean Spheres are a creation of Alistair Bimore allowing for magic energy to to funnelled into nearby objects given the correct attunement. While this was first used to provide powerful weapons to the people of Bimore with which they could repel the undead, it has since allowed for huge advancements for the every day life of citizens.
The power of a Sphere appears to be relative to their size with stones with the most powerful stones being at the heart of Bimore cities and powering magic defences but also transport, construction, and various day to day processes.
Little is known about the process to create these spheres other than it is a time and labour indusive process requiring years of work to produce the large spheres at the centre of Bimore cities. The secrete is closely guarded as it is what is giving Bimore their edge over the undead legions.