Unbreakable

You have faced many hardships, and grown stronger to overcome them.

• You gain an additional 1 hitpoint per level, including all previous levels, up to a maximum of 20.
• The first time your hitpoints drops to 0, you may choose to roll a DC15 constitution saving throw to retain consciousness, even at negative hitpoints. If you succeed, your speed drops to half of your maximum without bonuses, you fall prone, and you are unable to perform all attacks or cast any spells. You are still semi-conscious in this state, and are able to use your action to dodge an attack, disengage, or perform the help action. Falling prone like this breaks concentration. You are able to speak, but weakly.
• While in this state, you still perform your death saving throws as normal, and attacks made against you will only count as one death saving throw failure should they hit. You are not considered unconscious for any attack rolls made against you.
• You may spend your action to perform a DC15 Medicine Check on each of your turns with disadvantage. Each successful check will staunch the bleeding, which will prevent the next death saving throw from failing - but will not guarantee a success.
• Should you stabilize, you will stay knocked prone with 0 HP, but conscious. An ally within five feet of you can help you stand at the cost of one bonus action, which will revive you with 1 hitpoint. You may also spend 6 seconds (one round) to stand up on your own without assistance.
• Upon reviving after successfully using this feat, you are not able to benefit from this feat again until you complete 1d6 long rests, minus your constitution modifier, to a minimum of one long rest.