A compatability issue with Nyctophobia; While both mods are active, if the player changes the slugcat they are playing as, the game will freeze. Exceptionlog:

ArgumentException: key [disableWIP Night Walker WIP] is wrong; Only IsLetterOrDigit or underscore are allowed for key name
OptionInterface+ConfigHolder.Bind[T] (System.String key, T defaultValue, ConfigurableInfo info) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
ArenaSlugcatsConfigurator.Options+SlugcatObject..ctor (System.String name) (at <b1285c32d92b4b808cf49e0a0e0e0a84>:0)
ArenaSlugcatsConfigurator.Options+<>c.<GetModdedSlugcats>b__1_1 (System.String name) (at <b1285c32d92b4b808cf49e0a0e0e0a84>:0)
System.Collections.Generic.List`1[T].ConvertAll[TOutput] (System.Converter`2[TInput,TOutput] converter) (at <a1e9f114a6e64f4eacb529fc802ec93d>:0)
ArenaSlugcatsConfigurator.Options.GetModdedSlugcats () (at <b1285c32d92b4b808cf49e0a0e0e0a84>:0)
ArenaSlugcatsConfigurator.Plugin.IsSlucatDisabled (SlugcatStats+Name slugcat) (at <b1285c32d92b4b808cf49e0a0e0e0a84>:0)
ArenaSlugcatsConfigurator.Plugin.MultiplayerMenu_NextClass (On.Menu.MultiplayerMenu+orig_NextClass orig, Menu.MultiplayerMenu self, SlugcatStats+Name curClass) (at <b1285c32d92b4b808cf49e0a0e0e0a84>:0)
DMD<>?602758784.Hook<Menu.MultiplayerMenu::NextClass>?-411495424 (Menu.MultiplayerMenu , SlugcatStats+Name ) (at <62d3f4238e46409b9023b08b741c7fa7>:0)
Menu.MultiplayerMenu.Singal (Menu.MenuObject sender, System.String message) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.MenuObject.Singal (Menu.MenuObject sender, System.String message) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.MenuObject.Singal (Menu.MenuObject sender, System.String message) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.SimpleButton.Clicked () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.ButtonBehavior.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.ButtonTemplate.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.SimpleButton.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.MenuObject.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.PositionedMenuObject.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
Menu.Menu.Update () (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
DMD<Update>?602758784._Menu_MultiplayerMenu::Update (Menu.MultiplayerMenu this) (at <77057a8a10314866a7b3dfca5a9a086f>:0)
DMD<>?602758784.Trampoline<Menu.MultiplayerMenu::Update>?104415744 (Menu.MultiplayerMenu ) (at <d3f7dab7d305480c8485dda4759891b4>:0)
ArenaSlugcatsConfigurator.Plugin.MultiplayerMenu_Update (On.Menu.MultiplayerMenu+orig_Update orig, Menu.MultiplayerMenu self) (at <b1285c32d92b4b808cf49e0a0e0e0a84>:0)
DMD<>?602758784.Hook<Menu.MultiplayerMenu::Update>?-525442560 (Menu.MultiplayerMenu ) (at <7550cbb2fc0e4f029e5611749e39a2d2>:0)
MainLoopProcess.RawUpdate (System.Single dt) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
ProcessManager.Update (System.Single deltaTime) (at <1014ff9a5d9941ab9e645d4f5c9384a5>:0)
DMD<Update>?602758784._RainWorld::Update (RainWorld this) (at <5ac2b3e5d42c4d4aba7bcfb639836790>:0)
DMD<>?602758784.Trampoline<RainWorld::Update>?-1380745728 (RainWorld ) (at <c98db6a408084d32a072531e94d17bfd>:0)
Guardian.LogHooks.RainWorld_Update (On.RainWorld+orig_Update orig, RainWorld self) (at E:/RainWorldModding/Guardian/src/plugin/Hooks/LogHooks.cs:70)
UnityEngine.Debug:LogException(Exception)
Guardian.CloudLogger:LogAndUploadException(Exception) (at E:/RainWorldModding/Guardian/src/plugin/CloudLogger.cs:31)
Guardian.LogHooks:RainWorld_Update(orig_Update, RainWorld) (at E:/RainWorldModding/Guardian/src/plugin/Hooks/LogHooks.cs:74)
DMD<>?602758784:Hook<RainWorld::Update>?608836608(RainWorld)
DMD<>?602758784:Trampoline<RainWorld::Update>?-1598631424(RainWorld)
HealthBars.HealthBars:UpdatePatch(orig_Update, RainWorld)
DMD<>?602758784:Hook<RainWorld::Update>?938256896(RainWorld)
DMD<>?602758784:Trampoline<RainWorld::Update>?1317357056(RainWorld)
BeastMaster.BeastMaster:RainWorldOnUpdate(orig_Update, RainWorld)
DMD<>?602758784:Hook<RainWorld::Update>?1752977408(RainWorld)

ArgumentException: key [disableWIP Night Walker WIP] is wrong; Only IsLetterOrDigit or underscore are allowed for key name
at OptionInterface+ConfigHolder.Bind[T] (System.String key, T defaultValue, ConfigurableInfo info) [0x0006a] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at ArenaSlugcatsConfigurator.Options+SlugcatObject..ctor (System.String name) [0x00093] in <b1285c32d92b4b808cf49e0a0e0e0a84>:0
at ArenaSlugcatsConfigurator.Options+<>c.<GetModdedSlugcats>b__1_1 (System.String name) [0x00027] in <b1285c32d92b4b808cf49e0a0e0e0a84>:0
at System.Collections.Generic.List`1[T].ConvertAll[TOutput] (System.Converter`2[TInput,TOutput] converter) [0x0001a] in <a1e9f114a6e64f4eacb529fc802ec93d>:0
at ArenaSlugcatsConfigurator.Options.GetModdedSlugcats () [0x000f0] in <b1285c32d92b4b808cf49e0a0e0e0a84>:0
at ArenaSlugcatsConfigurator.Plugin.IsSlucatDisabled (SlugcatStats+Name slugcat) [0x0000e] in <b1285c32d92b4b808cf49e0a0e0e0a84>:0
at ArenaSlugcatsConfigurator.Plugin.MultiplayerMenu_NextClass (On.Menu.MultiplayerMenu+orig_NextClass orig, Menu.MultiplayerMenu self, SlugcatStats+Name curClass) [0x0000a] in <b1285c32d92b4b808cf49e0a0e0e0a84>:0
at DMD<>?602758784.Hook<Menu.MultiplayerMenu::NextClass>?-411495424 (Menu.MultiplayerMenu , SlugcatStats+Name ) [0x00014] in <62d3f4238e46409b9023b08b741c7fa7>:0
at Menu.MultiplayerMenu.Singal (Menu.MenuObject sender, System.String message) [0x0090d] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.MenuObject.Singal (Menu.MenuObject sender, System.String message) [0x00016] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.MenuObject.Singal (Menu.MenuObject sender, System.String message) [0x00008] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.SimpleButton.Clicked () [0x00000] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.ButtonBehavior.Update () [0x0012c] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.ButtonTemplate.Update () [0x00006] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.SimpleButton.Update () [0x00000] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.MenuObject.Update () [0x00010] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.PositionedMenuObject.Update () [0x00000] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at Menu.Menu.Update () [0x00231] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at DMD<Update>?602758784._Menu_MultiplayerMenu::Update (Menu.MultiplayerMenu this) [0x00076] in <77057a8a10314866a7b3dfca5a9a086f>:0
at DMD<>?602758784.Trampoline<Menu.MultiplayerMenu::Update>?104415744 (Menu.MultiplayerMenu ) [0x00020] in <d3f7dab7d305480c8485dda4759891b4>:0
at ArenaSlugcatsConfigurator.Plugin.MultiplayerMenu_Update (On.Menu.MultiplayerMenu+orig_Update orig, Menu.MultiplayerMenu self) [0x0003a] in <b1285c32d92b4b808cf49e0a0e0e0a84>:0
at DMD<>?602758784.Hook<Menu.MultiplayerMenu::Update>?-525442560 (Menu.MultiplayerMenu ) [0x00014] in <7550cbb2fc0e4f029e5611749e39a2d2>:0
at MainLoopProcess.RawUpdate (System.Single dt) [0x0001a] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at ProcessManager.Update (System.Single deltaTime) [0x001ae] in <1014ff9a5d9941ab9e645d4f5c9384a5>:0
at DMD<Update>?602758784._RainWorld::Update (RainWorld this) [0x01629] in <5ac2b3e5d42c4d4aba7bcfb639836790>:0
at DMD<>?602758784.Trampoline<RainWorld::Update>?-1380745728 (RainWorld ) [0x00020] in <c98db6a408084d32a072531e94d17bfd>:0
at Guardian.LogHooks.RainWorld_Update (On.RainWorld+orig_Update orig, RainWorld self) [0x00002] in E:\RainWorldModding\Guardian\src\plugin\Hooks\LogHooks.cs:70
UnityEngine.StackTraceUtility:ExtractStringFromException(Object)
Guardian.CloudLogger:LogAndUploadException(Exception) (at E:\RainWorldModding\Guardian\src\plugin\CloudLogger.cs:30)
Guardian.LogHooks:RainWorld_Update(orig_Update, RainWorld) (at E:\RainWorldModding\Guardian\src\plugin\Hooks\LogHooks.cs:74)
DMD<>?602758784:Hook<RainWorld::Update>?608836608(RainWorld)
DMD<>?602758784:Trampoline<RainWorld::Update>?-1598631424(RainWorld)
HealthBars.HealthBars:UpdatePatch(orig_Update, RainWorld)
DMD<>?602758784:Hook<RainWorld::Update>?938256896(RainWorld)
DMD<>?602758784:Trampoline<RainWorld::Update>?1317357056(RainWorld)
BeastMaster.BeastMaster:RainWorldOnUpdate(orig_Update, RainWorld)
DMD<>?602758784:Hook<RainWorld::Update>?1752977408(RainWorld)

Is incompatible with the new QuirrelCat mod. Character problem because this doesn't read periods so it breaks the menu, and arena mode.

ArgumentException: key [disablekusmhakko.quirrelcat] is wrong; Only IsLetterOrDigit or underscore are allowed for key name
OptionInterface+ConfigHolder.Bind[T] (System.String key, T defaultValue, ConfigurableInfo info) (at <a117a2e773414632b51933d2ae7f2aca>:0)
ArenaSlugcatsConfigurator.Options+SlugcatObject..ctor (System.String name) (at <6e3a1ce989634545b2b9bb87565680aa>:0)
ArenaSlugcatsConfigurator.Options+<>c.<GetModdedSlugcats>b__1_1 (System.String name) (at <6e3a1ce989634545b2b9bb87565680aa>:0)
System.Collections.Generic.List`1[T].ConvertAll[TOutput] (System.Converter`2[TInput,TOutput] converter) (at <695d1cc93cca45069c528c15c9fdd749>:0)
ArenaSlugcatsConfigurator.Options.GetModdedSlugcats () (at <6e3a1ce989634545b2b9bb87565680aa>:0)
ArenaSlugcatsConfigurator.Plugin.IsSlucatDisabled (SlugcatStats+Name slugcat) (at <6e3a1ce989634545b2b9bb87565680aa>:0)
ArenaSlugcatsConfigurator.Plugin.MultiplayerMenu_NextClass (On.Menu.MultiplayerMenu+orig_NextClass orig, Menu.MultiplayerMenu self, SlugcatStats+Name curClass) (at <6e3a1ce989634545b2b9bb87565680aa>:0)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition.Hook<Menu.MultiplayerMenu::NextClass>?-297014784(Menu.MultiplayerMenu,SlugcatStats/Name)
(wrapper dynamic-method) Menu.MultiplayerMenu.DMD<Menu.MultiplayerMenu::Singal>(Menu.MultiplayerMenu,Menu.MenuObject,string)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition.Trampoline<Menu.MultiplayerMenu::Singal>?526688768(Menu.MultiplayerMenu,Menu.MenuObject,string)
CustomRegions.Arena.ChallengeMenu.MultiplayerMenu_Singal (On.Menu.MultiplayerMenu+orig_Singal orig, Menu.MultiplayerMenu self, Menu.MenuObject sender, System.String message) (at <dcb6a937f60c4d5eb2f9ca4dba19374c>:0)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition.Hook<Menu.MultiplayerMenu::Singal>?-899134976(Menu.MultiplayerMenu,Menu.MenuObject,string)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition.Trampoline<Menu.MultiplayerMenu::Singal>?2025830400(Menu.MultiplayerMenu,Menu.MenuObject,string)

Relevant parts of the exception log.

same exception for diver from reclaiming entropy mod

when loading into arena, it give the white screen of death. as of the watcher update..

crash my game

slug cat modifiers don't work

remix menu for the mod is not working, so i dont get to randomize my scug each round :(
(says it does not have a menu)

@grimm_ace maybe applying Merge fix could help? Sometimes it happens to me but when apply that mod it should work and if it's already applied I just change it of place and apply it again.