When you die in an Elite STF you will most likely get an injury. Injuries will reduce the damage you do as well as the ability to survive. The combined affect of the injuries stack perfectly. There are three stages of injuries: Minor, Major, and Critical. You will need the corresponding Regenerator to heal the same level of injuries. Critical Regenerators are rare and expensive, but you only get critical injuries after dying with an existing injury. Therefore, heal your injuries every time you die.