Why am I getting a crash error?

[15:19:46] [main/INFO] [LaunchWrapper/]: Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
[15:19:46] [main/DEBUG] [FML/]: Injecting coremod LoadingPlugin {cofh.asm.LoadingPlugin} class transformers
[15:19:46] [main/TRACE] [FML/]: Registering transformer cofh.asm.CoFHClassTransformer
[15:19:46] [main/DEBUG] [FML/]: Injection complete
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin for LoadingPlugin {cofh.asm.LoadingPlugin}
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin LoadingPlugin
[15:19:46] [main/DEBUG] [CoFHASM/]: Adding CoFHAT: CoFHLib_at.cfg from: CoFHLib-[1.7.10]1.2.1-185.jar
[15:19:46] [main/DEBUG] [FML/]: Coremod plugin class LoadingPlugin run successfully
[15:19:46] [main/INFO] [LaunchWrapper/]: Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
[15:19:46] [main/DEBUG] [FML/]: Injecting coremod TLLoadingPlugin {com.gildedgames.util.threadedlighting.TLLoadingPlugin} class transformers
[15:19:46] [main/TRACE] [FML/]: Registering transformer com.gildedgames.util.threadedlighting.asm.TLTransformer
[15:19:46] [main/DEBUG] [FML/]: Injection complete
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin for TLLoadingPlugin {com.gildedgames.util.threadedlighting.TLLoadingPlugin}
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin TLLoadingPlugin
[15:19:46] [main/DEBUG] [FML/]: Coremod plugin class TLLoadingPlugin run successfully
[15:19:46] [main/INFO] [LaunchWrapper/]: Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
[15:19:46] [main/DEBUG] [FML/]: Injecting coremod MalisisCorePlugin {net.malisis.core.asm.MalisisCorePlugin} class transformers
[15:19:46] [main/TRACE] [FML/]: Registering transformer net.malisis.core.util.chunkcollision.ChunkCollisionTransformer
[15:19:46] [main/INFO] [malisiscore/]: [ChunkCollisionTransformer] Hook registered for net.minecraft.world.World
[15:19:46] [main/INFO] [malisiscore/]: [ChunkCollisionTransformer] Hook registered for net.minecraft.world.World
[15:19:46] [main/INFO] [malisiscore/]: [ChunkCollisionTransformer] Hook registered for net.minecraft.item.ItemBlock
[15:19:46] [main/INFO] [malisiscore/]: [ChunkCollisionTransformer] Hook registered for net.minecraft.network.NetHandlerPlayServer
[15:19:46] [main/TRACE] [FML/]: Registering transformer net.malisis.core.util.chunkblock.ChunkBlockTransformer
[15:19:46] [main/INFO] [malisiscore/]: [ChunkBlockTransformer] Hook registered for net.minecraft.world.chunk.Chunk
[15:19:46] [main/DEBUG] [FML/]: Injection complete
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin for MalisisCorePlugin {net.malisis.core.asm.MalisisCorePlugin}
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin MalisisCorePlugin
[15:19:46] [main/DEBUG] [FML/]: Coremod plugin class MalisisCorePlugin run successfully
[15:19:46] [main/INFO] [LaunchWrapper/]: Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
[15:19:46] [main/DEBUG] [FML/]: Injecting coremod EnderCorePlugin {com.enderio.core.common.transform.EnderCorePlugin} class transformers
[15:19:46] [main/TRACE] [FML/]: Registering transformer com.enderio.core.common.transform.EnderCoreTransformer
[15:19:46] [main/TRACE] [FML/]: Registering transformer com.enderio.core.common.transform.EnderCoreTransformerClient
[15:19:46] [main/DEBUG] [FML/]: Injection complete
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin for EnderCorePlugin {com.enderio.core.common.transform.EnderCorePlugin}
[15:19:46] [main/DEBUG] [FML/]: Running coremod plugin EnderCorePlugin
[15:19:46] [main/DEBUG] [FML/]: Coremod plugin class EnderCorePlugin run successfully
[15:19:46] [main/INFO] [LaunchWrapper/]: Loading tweak class name cpw.mods.fml.common.launcher.TerminalTweaker
[15:19:46] [main/INFO] [LaunchWrapper/]: Calling tweak class cpw.mods.fml.common.launcher.TerminalTweaker
[15:19:46] [main/INFO] [STDOUT/]: [optifine.OptiFineForgeTweaker:dbg:56]: OptiFineForgeTweaker: getLaunchArguments
[15:19:46] [main/INFO] [LaunchWrapper/]: Launching wrapped minecraft {net.minecraft.client.main.Main}
[15:19:46] [main/INFO] [me.guichaguri.betterfps.transformers.EventTransformer/]: Patching Game Start…
[15:19:46] [main/INFO] [STDOUT/]: [micdoodle8.mods.miccore.MicdoodleTransformer:printLog:1989]: Galacticraft successfully injected bytecode into: sa (1 / 1)
[15:19:46] [main/ERROR] [LaunchWrapper/]: Unable to launch
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:?]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
Caused by: java.lang.NoClassDefFoundError: net/minecraft/entity/Entity
at net.minecraft.client.main.Main.main(SourceFile:72) ~[Main.class:?]
… 6 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.entity.Entity
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?]
at net.minecraft.client.main.Main.main(SourceFile:72) ~[Main.class:?]
… 6 more
Caused by: java.lang.ClassFormatError: Duplicate method name&signature in class file net/minecraft/entity/Entity
at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?]
at java.lang.ClassLoader.defineClass(ClassLoader.java:760) ~[?:?]
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[?:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?]
at net.minecraft.client.main.Main.main(SourceFile:72) ~[Main.class:?]
… 6 more
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: cpw.mods.fml.relauncher.FMLSecurityManager$ExitTrappedException
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: at cpw.mods.fml.relauncher.FMLSecurityManager.checkPermission(FMLSecurityManager.java:25)
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: at java.lang.SecurityManager.checkExit(SecurityManager.java:761)
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: at java.lang.Runtime.exit(Runtime.java:107)
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: at java.lang.System.exit(System.java:971)
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: at net.minecraft.launchwrapper.Launch.launch(Launch.java:138)
[15:19:46] [main/INFO] [STDERR/]: [java.lang.Throwable$WrappedPrintStream:println:748]: at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

Caused by: java.lang.ClassFormatError: Duplicate method name&signature in class file net/minecraft/entity/Entity

Typically that is caused by two or more mods/plugins conflicting with one and another.

Sadly your crash doesnt state what the two mods are, but logic would state that one of them is one of the mods that had sent a message to your console before the crash