@AiratomeUsing Hit Die = Roll + Con mod. What if con is so low the roll + ( – 3) Con Mod = negative? No healing? min of +1 hp? Lose HP? minimum 1

— Mike Mearls (@mikemearls) March 26, 2016

You regain no hit points if you spend a Hit Die and your Constitution modifier reduces the total to 0 or lower. #DnD https://t.co/MM0tm9tekr

— Jeremy Crawford (@JeremyECrawford) April 1, 2016