[RPG] How to determine the result of a Saving Throw


I'm a pretty new player, and I'm building a bard in D&D 5e. I understand how saving throws work in general, but I am a little confused about one thing. Say I cast Blindness/Deafness on a humanoid. They must then make a Constitution saving throw. My question is: what value do they have to roll in order to make the save? Does their roll (plus their constitution modifier) have to beat my constitution (plus my modifier)? This is more of a general player question than one specific to the Bard or that spell.

Best Answer

Saving throws are always made against a DC, and in the case of casting spells there is a formula to work out the required DC. From the Basic Rules on spellcasting:

Saving Throws

Many spells specify that a target can make a saving throw to avoid some or all of a spell's effects. The spell specifies the ability that the target uses for the save and what happens on a success or failure.

The DC to resist one of your spells equals 8 + your spellcasting ability modifier + your proficiency bonus + any special modifiers.

And as the Bard class description says:

Spellcasting Ability

Charisma is your spellcasting ability for your bard spells. Your magic comes from the heart and soul you pour into the performance of your music or oration. You use your Charisma whenever a spell refers to your spellcasting ability. In addition, you use your Charisma modifier when setting the saving throw DC for a bard spell you cast and when making an attack roll with one.

Spell save DC = 8 + your proficiency bonus + your Charisma modifier

So your bard spells have save DC based on your charisma modifier and proficiency bonus as described above. In general, whenever a class or racial feature allows you to cast spells somehow, its description will clarify what the relevant spellcasting ability modifier is, if any, so that you can work out the saving throw DC.