Your natural affinity for passing out in the face of danger helps to ensure that the battle stops before it turns lethal.
Benefit: Whenever you are reduced to 1/5th your maximum hit points, or 10 hit points or less (whichever is less), you immediately fall unconscious unless you succeed on a Will save (DC 10). A natural 1 on this Will save always results in a failure. This unconsciousness lasts for 1d4 hours. While you are unconscious in this way, any creature with an Intelligence score of 3 or greater must succeed on a Will save (DC 10 + ½ your Hit Dice + your Charisma modifier) each time it tries to attack you or be unable to do so. Creatures with an Intelligence score of 2 or less can attack you regardless.
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