So tried to launch Epic fight mod with Origins mod and several other's. In the game everything works perfectly. But whenever i try to add new items for switching between mining and fighting mod, Minecraft instantly crashes. It happens only in Auto Switching items menu when i press the plus button. The menu with a list of a blocks to select just doesn't appear, only a crash. Other mod options seem to work perfectly fine. Crash doesn't happen without the mods. Texture packs don't affect the issue. I tested this on 2 mod versions - 5.1.1 and 5.1.2.

Mods i've been using except Epic Fight mod:
SereneSeasons-1.16.5-4.0.1.121-universal - mod that change seasons in the game
Genesis-0.5.1 - required library for Orgins mod
added_origins_mod_forge-V2.0.0 - adds more origins
caelus-forge-1.16.5-2.1.3.1 - required library for Orgins mod
tl_skin_cape_forge_1.16.5-1.17 - this mod doesn't affect anything, as i used before and it worked
Origins-1.16.5-0.7.3.9-forge
architectury-1.21.31-forge - required library for Orgins mod
cloth-config-4.11.26-forge.jar - required library for Orgins mod

Crash report (always the same on any version)
crash-2021-10-11_21.41.21-client.txt

P.S.: I perfectly understand that there are some mods that could be simply incompatible with Epic Fight mod, but i still hope that this is a solvable issue.

The crash report says that the direct reason for this crash was caused by SereneSeasons mod. Could you report this to the author of SereneSeasons mod? (I can't find the reason because its source is closed.)

Oh, okay. And i actually found a temporary solution (for anyone who wants to use both mods at the same time). You can replace SerenSeasons from the mods folder, launch minecraft, configure necessary items and put the mod back in the folder. The issue still remains, but at least your items and tools for switching save.