Praise the effort to try to explain untold story of the conjunction of sphere, but it might just be an opportunity to milk the golden cow.
Sooner or later it had to happen though, this is a "plothole" completely missing in the books and (3rd) game.
Apart for some terms from witcher universe, it is a stand alone story, it just felt completely unrelated to witchers.
First witcher battles: negligible.
Conquer new worlds: patrol of 6 soldiers.
It is fine for a four episode miniseries.