Narcissistic rage is a reaction to narcissistic injury, a perceived threat to a narcissist’s self-esteem or self-worth. The rages can take two forms: explosive and pernicious, or passive-aggressive. The explosive and pernicious rages are highly volatile outbursts which may be verbal or physical, whereas the passive-aggressive rages are more likely to be experienced when the narcissist withdraws into sulky silent treatment as a means of punishment.
It is a mistake to confuse narcissistic rage with anger, although the two may be similar, there are differences. The narcissist can be triggered into an extreme rage by something that would normally only provoke angry feelings in another person. For example, they can fly into a rage by something that would appear relatively trivial in other company; such as disagreeing with them, or preventing them from carrying out their desired wishes (no matter how grandiose their fantasies are). In fact, any time you accidentally (or deliberately) trigger any (conscious/unconscious) shameful feeling, the narcissist will go into a predictable rage.