Disadvantage

A number of situations and conditions can give entities Disadvantage on their dice roll.
When rolling dice with Disadvantage, roll 2 dice separately instead of 1. Use the lower of the two results.
Disadvantage does not stack : having multiple sources of Disadvantage on a dice roll stills only roll twice. Having both Advantage and disadvantage on a roll only roll a single die, even if they have multiple sources of either.