that sounds like a really interesting story premise! i bet it creates a lot of interesting dynamics~

but yeah, i do see how that can be a problem. i'm not sure how much advice i can offer without knowing all the details of your story, but the first thing that came to mind is that there are other ways you can 'pay the price' with something other than your life. i'm not sure what your world's magic system is, but since it's a fantasy genre, you can definitely play around with the sort of things characters can give up in order to maintain balance. some ideas that come to mind:

-their memories/emotions/identity

-their home/important possessions

-their relationship to other characters

-their magical abilities

-their rank/title/position

-the goals they've been reaching for the entire book

there are so many posibilities for ways characters can pay the price without death. not only does this keep the character alive in the story, but it can also create new situtations to explore the character's personality and move the plot forward.

you can also introduce new characters who can continue the story after your initial main characters die, although i can see some issues with that (it could overcomplicate things, you might not get to flesh out each of your characters to the extent that you'd like to, etc).

i hoped this was sort of helpful! good luck with your story! it sounds really cool :D 

An idea could be to kill off the main characters and have the side characters live on, or like @Peri said, to do another cast of characters. Though more details would be helpful.

I agree, an anthology would probably work, but it sounds like it has an overarching plot. since attatchment to the main character(s) is basically the most important thing in a story (and i'm not kidding, even tension goes down if you don't care about the person who it's happening to) you'd probably not want to have a new character per book. or you could build importance for the next main character during the book while the other character dies, if they don't all strictly have to die. 

also since you said there's a lot of characters: how few can you get away with? if you have fewer characters, you have more time to spend on each one, and readers will be able to remember them all XD i know nobody likes getting rid of characters, but you can always combine them, and it makes for a better story in the end the vast majority of the time. 

For instance, if you have a character who opens something and another who tries to get it into a box: why can't they be the same? although it's rarely that simple in practice. 

more details would be really helpful though. 

also, in general, you want to be able to compromise and change things/not get too attached to things being one specific way if it might make a worse story. so find the parts of the story you're most interested in (because then you'll have the best time writing it and it won't, like, veer off course because you want to write about something that isn't important to the plot as much) and center the rest of it around that.

you'll notice that a lot of this is about condensing things and making them simpler, which is generally a very good idea. if the point of a story is to be enjoyable, it's generally better to not have 20 seperate plot threads and 10 main characters and even more side characters, all of which you have to keep track of. this doesn't mean you can't have complexity; it just means you should be purposeful with it. the less unnecessarily complex other things are, the more you can focus on the central complexity as well. and, like, some complex things may be more interesting than others; readers are more likely to enjoy having a multifaceted war drama with many sides than unnecessary characters, some of whom they won't be attatched to and others who they'll like and not get enough of.  

you could go with a reincarnation type thing: these characters are reborn as the same sort of person, or the same sort of hero, and maybe they have some of their previous selves memories? just so they're a little less dead, since you're so attached to them.

okay, yeah, i would love to read that.

No way pangolin that's so cool!! I'd love to read your novel (100k??? How??) and any plans you have for your upcoming project, which sounds so cool already.