Suffocating

You are out of breath and cannot breathe.
  You automatically fail Death Saves and cannot become Stable or regain HP while Suffocating.
  At the beginning of each of your turns while Suffocating, make a DC 10 Constitution Save, which has Disadvantage if you took damage or a strenuous action in the past round. 
  If you succeed, then you can act as normal this turn, though strenuous actions still give Disadvantage on future saves against suffocation. 
  If you fail, then you drop to 0 HP and begin dying. 
  More severe than Strangled.