The creature you touch gains protection against either a specific damage type (slashing, poison, fire, radiant, and the like) or a category of creature (giant, beast, elemental, monstrosity, and so forth) that you name when the spell is cast. For the next 24 hours, the target has advantage on saving throws involving that type of damage or kind of creature, including death saving throws if the attack that dropped the target to 0 hit points is affected by this spell. A character can be under the effect of only a single not this day! spell at one time; a second casting on the same target cancels the preexisting protection.