Hello, on the new Forge update (36.2.20) creating or loading any world gets stuck forever around the 70-80% mark. Checking the logs, there seems to be an infinitely looping stack overflow error, in some way related to the Log4J file. According to the forge changelog, this file is what was updated in this new version, to fix a security vulnerability. This is also why downgrading Forge to fix this issue temporarily isn't an option.
As epic fight mod is the only one mentioned in the error, I figured the best bet would be to report this in your issue tracker. I apologize in advance in case my assumption turns out to be wrong.

Here is the error in question:

java.lang.StackOverflowError
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at net.minecraftforge.eventbus.EventBus.lambda$handleException$13(EventBus.java:316)
at org.apache.logging.log4j.util.LambdaUtil.get(LambdaUtil.java:77)
at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:1999)
at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1844)
at org.apache.logging.log4j.spi.AbstractLogger.error(AbstractLogger.java:785)
at net.minecraftforge.eventbus.EventBus.handleException(EventBus.java:316)
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:307)
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:283)
at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:597)
at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:591)
at net.minecraftforge.common.capabilities.CapabilityProvider.doGatherCapabilities(CapabilityProvider.java:83)
at net.minecraftforge.common.capabilities.CapabilityProvider.getCapabilities(CapabilityProvider.java:91)
at net.minecraftforge.common.capabilities.CapabilityProvider.getCapability(CapabilityProvider.java:173)
at net.minecraftforge.common.capabilities.ICapabilityProvider.getCapability(ICapabilityProvider.java:48)
at yesman.epicfight.events.CapabilityEvent.attachItemCapability(CapabilityEvent.java:23)
at net.minecraftforge.eventbus.ASMEventHandler_1138_CapabilityEvent_attachItemCapability_AttachCapabilitiesEvent.invoke(.dynamic)
at net.minecraftforge.eventbus.ASMEventHandler.invoke(ASMEventHandler.java:85)
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:302)
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:283)
at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:597)
at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:591)
at net.minecraftforge.common.capabilities.CapabilityProvider.doGatherCapabilities(CapabilityProvider.java:83)
at net.minecraftforge.common.capabilities.CapabilityProvider.getCapabilities(CapabilityProvider.java:91)
at net.minecraftforge.common.capabilities.CapabilityProvider.getCapability(CapabilityProvider.java:173)
at net.minecraftforge.common.capabilities.ICapabilityProvider.getCapability(ICapabilityProvider.java:48)
at yesman.epicfight.events.CapabilityEvent.attachItemCapability(CapabilityEvent.java:23)
at net.minecraftforge.eventbus.ASMEventHandler_1138_CapabilityEvent_attachItemCapability_AttachCapabilitiesEvent.invoke(.dynamic)
at net.minecraftforge.eventbus.ASMEventHandler.invoke(ASMEventHandler.java:85)
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:302)
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:283)
at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:597)
at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:591)
at net.minecraftforge.common.capabilities.CapabilityProvider.doGatherCapabilities(CapabilityProvider.java:83)
at net.minecraftforge.common.capabilities.CapabilityProvider.getCapabilities(CapabilityProvider.java:91)
at net.minecraftforge.common.capabilities.CapabilityProvider.getCapability(CapabilityProvider.java:173)
at net.minecraftforge.common.capabilities.ICapabilityProvider.getCapability(ICapabilityProvider.java:48)
at yesman.epicfight.events.CapabilityEvent.attachItemCapability(CapabilityEvent.java:23)

This last section then loops indefinitely. There seems to be no way to get out of this except for closing the game from the task manager. The window isn't frozen or non-responding, everything seems to be normal, but the X button doesn't do anything.
I unfortunately do not have a way to test with a server at the moment, so I have no clue if this only happens in singleplayer or any world-loading at all.
Thank you for your time.

Try the Forge version 36.2.0 which is the development environment.