How can I determine the next chapter based on RNG?

[Brigtel]

Hello, I just got into fire emblem rom hacking, and had an idea for a rom hack but there is something I can't find the solution to. I wanted to make the game into a dungeon crawler style game. For this I am using FEbuilder,  and using a base of Fire Emblem The Sacred Stones. In order to begin actually turning my idea into a rom hack, I first needed to make sure that every concept that makes up my idea actually works. Pretty much the only thing that is really blocking me is finding a way for the end of a chapter to lead to another chapter selected at random. I know there is a way for the next chapter to be selected by something happening in the game, since that is essentially what the Eirika-Ephraim split is. It also seems rather simple to generate a random number and have a certain event happen or not based on the value of that number, but I simply haven't found a way to do that. I also tried seeing how the game makes the Eirika-Ephraim split by analyzing the events but it was confusing and I figured asking here would be better, since even knowing how the game does it wouldn't solve the problem. So, does anyone know how I could put a condition on a "Go to next Chapter" event and have that condition be determined by RNG? I also have 2 other, less important questions that I didn't find an answer to while researching: Can I preserve the health of characters through chapters? Can the Chapter list be extended?            

[Von Ithipathachai]

You may want to consult FEUniverse about something like this if you insist on sticking with hacking.  It sounds like something that might require ASM if it's not something FEBuilder is capable of doing natively.

Alternatively, if you're willing to spend $60 and/or wait for it to go on sale on Steam, RNG-based chapter progression is something SRPG Studio can do easily.  I also know of maybe one or two roguelike SRPG Studio projects in the works by members of the English SRPG Studio community.  Heck, even the project I'm working on for Ghast's Make a Fun Chapter contest works on similar principles of RNG-determined environment types.

[Topaz Light]

This sounds like something that would very quickly have apocalyptic consequences for your hack's stability if you wanna do it as that, although you are correct in that it should be simple to just generate a random number, then check it to determine what happens next.

You may be better off just trying to do it in a different engine because of the kind of wreck it would be to actually implement in a hack.

[Brigtel]

Well, with the quarantine I finally have some more time to give to this. For the RNG I actually have an idea, it seems functional just very impractical: when a chapter ends, I would go to a custom chapter where a battle will happen between two characters. The outcome of the battle would depend on whether or not a character got a critical hit, and the outcome of the battle can be used to determine which chapter to go to next. Thanks for trying to help, but I get that this is a very complicated concept to correctly implement especially for a complete beginner like me.