Closing on this week, I wanted to talk about a cosmic event that shaped the state of the Witcher universe as we see it in books and games. This isn't going to be a very lengthy post, because the topic that I'm covering here despite being very important in the lore, isn't extensively explained by Sapkowski. The Conjunction of Spheres (Koniunkcja Sfer) was a catastrophy in space that happened way over 1000 years before the events of the books. The name of it suggests that what caused it was the planets lining up in a straight line. It opened the gates between worlds. This was a process as different gates opened at different times, because elves from the Aen Elle world came to the witcher world many years before humans from our world (also Vesemir, while teaching Ciri about necrophages, says that they are a relict of a period of the permeation of spheres, that also suggest that the aftermath of the Conjunction lasted many years). It also brought creatures from many different worlds, that were then refered to as monsters, including e.g. necrophages and vampires. It also "created" the magic – I believe that the magic was always in the nature in this world, but the energy released during the conjunction (maybe at the end of it, when the gates were closing) alowed people to discover it and study its secretrs. The gates eventually closed, leading Aen Elle elves, whose planet was dying to desperately seek a way to open the gates between worlds back, so they can evacuate their race to a new world. They've started research on the genetics – created the "Elder Blood", but this is a story for another post.
If i were to make a card out of it it would be something like this probably: