Minecraft wiki entry for Half_hearted_hardcore, associated text: Half hearted hardcore, or half a heart hardcore, is self-explanatory. It is a custom difficulty which has all the hardcore and ultra hardcore restrictions, but you are stuck on half a heart, cannot regenerate at all, and if you take any damage from anything, from a boss mob to a llama, you will die, and, on top of all of that, the world will be deleted.