Making frightening threats is an important life skill. If you make a threat that doesn't instill fear, you just wasted your time and made your adversary think the exact opposite of what you wanted.
There are two basic kinds of threats: the explicit kind that removes any
doubt about the intentions of the person issuing the treat, and the
vague kind that lets your imagination fill in the blanks, leaving you to scare yourself. One threat is
saying, "If you do X, then I will kill you." whereas the other says, "Do
X and see what happens.".
Everyone aspires to make great and harrowing threats, so let's learn from the best.