Caused by: java.lang.ClassNotFoundException: mchorse.metamorph.api.models.IMorphProvider
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
It is actually not being able to find an interface your EntityActor implements, which you can see way down the stacktrace as it can't find the IMorphProvider interface. Are you sure the mod that interface belongs to is loaded when you run your mod?