onKilledMob

@SubscribeEvent
        public void onEntityDeath(LivingDeathEvent event) {

            if (event.getEntity() instanceof EntityPlayer) {
                EntityPlayer player = (EntityPlayer) event.getSource().getSourceOfDamage();

                if (entity.inventory.getCurrentItem() != null && entity.inventory.getCurrentItem().getItem() == mcreator_animaLuciferiSwordTool.block) {
                    if (entity instanceof EntityLivingBase)
                        ((EntityLivingBase) entity).addPotionEffect(new PotionEffect(MobEffects.SPEED, 40, 0));

                }

            }
        }