SOLVED!
things I did after help from the people in this thread(original classes in the OP are all updated):
- changed the globalID entity registry to EntityRegistry.registerModEntity,
- moved RenderingRegistry.registerEntityRenderingHandler(EntityHorror.class, new RenderHorror(Minecraft.getMinecraft().getRenderManager(), new ModelHorror(), 1.0F)); from init() to preInit() in the main class.
- removed overridden entityInit() method from the EntityHorror class.
- removed this.getAttributeMap().registerAttribute(reinforcementChance).setBaseValue(this.rand.nextDouble() * net.minecraftforge.common.ForgeModContainer.zombieSummonBaseChance); from applyEntityAttributes method of the EntityHorror class.
Thank you all for your help.