House rule: Stress Situations

This is a house rule - As a DM it is your decision how to use it

Sometimes enemies starts an attack on a single target and start a stress situation. They risk their life to attack you, however you attack back. The monster can kill you if you miss!

How a stress situation starts:

If a monster is low HP (1 Hp and start HP > 10) it will scarifies it self to kill you. The monster rolls an 1d4 and you an 1d8 if your value is greater than the monsters value, you kill the monster instant. If you miss, the monster makes an attack against you. You can't get help for this attack. You get true damage => No way to block any damage.