Players often refer to their characters being taken down during battle as “dying” or having “died” and while this is common to refer to having your character being KO’ed as such, actual death has a much more literal meaning in the world of DotC.
Simply being taken down and respawning in your Garrison does not mean your character died, they just got taken down in battle and were taken back to home base, so to speak. However if the M.O.B. mentioned that there is a danger of being killed, it does not mean you might be taken down, it is actually speaking of permanent character death. So when a storyline entity is speaking of the dangers of a task and mentions death, do take that warning as such.
As mentioned previously, characters can suffer injury during battle, in particularly there is a type of injury referred to as critical injury which is a lethal wound inflicted to your character. There are times, depending on circumstances and other factors, where a critical injury can be lethal instantaneously; however most of the time a character that has entered a critical injury state will be taken to intensive care, and resources can be used to save them.
Permanent character death, or permadeath as some will call it, will cause you to lose the character and they will have died as per the records of the storyline. You will lose most, if not all items the character had on them, with the exception of item mall items (IF you have purchased item mall insurance). While your character is in a critically injured state, you will also not have access to the character, however if they are saved by using medical resources to recover them, you will have the character returned to your account once this is done. Keep in mind, however, that critical injuries have a 3 day timer to save the character before they succumb to their wounds.
Here are a few things that can help or damage your chances of getting perma killed:
Regular or Neutral Defenders have a 40% chance of getting killed.
Premium Defenders have a 30% chance of getting killed.
Platinum Defenders have a 20% chance of getting killed.
Villainous Defenders have a 50% chance of getting killed.
Heroic Defenders have a 30% chance of getting killed.
(Note: Even though the chances aid or damage, you getting “perma killed” is also highly tied to your storyline.)