Homebrew:Death Defier

(OOC: This is an implementation of the Death Defier feat from The Crooked Moon)
Prerequisite: 4th level or higher
When the hand of death reaches for your soul, you have found a way to reject its call. You gain the following benefits.
- Ability Score Increase.
- Increase your Constitution score by 1, to a maximum of 20.
- Cling to Life.
- You add your Constitution modifier (minimum of 1) to death saving throws.
- Enduring Vitality.
- If an effect would kill you outright without death saving throws or would reduce you directly to 0 hit points without dealing damage, you are instead reduced to a number of hit points equal to your level. You can't use this benefit again until you finish a long rest.