oh honey. is that spell going to be undone? even if she doesn't have the loyalty to stay by him, the archmage helped her realize something. but for plot progression... character development... this is just my speculation if second prince is ML. this death is necessary to move forward with Kasia's character, any lingering relationships will carry its own burden. the loss of the archmage, a center piece will also be of great benefit to move this war forward, to move this story more quickly - as the archmage is carrying the front lines, without him...
christ do I have to wait for another mass update to bleed out my heart? I was already ready but this cliff has dropped some hints.
I also like the artistic interpretation of the flashbacks (simple editing) to draw a progression of time - the blurrier the image, the earlier it was chronologically. this arc has been fun, and I'm dearly going to miss Kasia's Estelle persona - hungry hungry...