Trauma Induced Endurance

You have been through a lot. At some point in your life you suffered so much trauma that you developed superhuman endurance. When you fall below 0 hit points you immediately recover 1 hit point. You do not regain this skill until a long rest or until your trauma is triggered by something that reminds you of it. The charges of this skill do not stack, the trigger can only re-activate the feat after it has already been used once per long rest. 

This feat can be activated no more than twice per long rest. You can choose up to two triggers (related to your trauma) to be agreed with your DM.