D&D 5E Completing a Bard Spell Roll

[AzureShin]

So long and the short of it is i have no idea what to add. I believe it is Charisma modifier + proficiency. Am i wrong?

 

[PnPgamer]

what spell roll? Spell attack? its caster stat modifier + proficiency.

if it is a save DC you're looking for, it is 8+ stat mod + proficiency.

 

[dmnqwk]

If you don't know what is the right dice, ask yourself one question:

1) Is this a roll for damage?

If the answer is no, you're almost certainly rolling a D20. And for Attacks, Checks and Saves (which cover pretty much all the rolls) you add 2 numbers.

A) Firstly, add your proficiency modifier if you are proficient. You are always proficient in your own spells, as well as any appropriate skills, weapons and saving throws.
B) Secondly, add the ability associated with the roll - Str/Dex/Con/Int/Wis/Cha depending on what skill, save or attack it is.

As a note, Spells which require you to roll to hit are now attacks, either Melee Spell Attack or Ranged Spell Attack, and follow the same rules as any other Attack (which is to say D20 + proficiency + ability modifier) but use your Spellcasting Ability in lieu of Strength/Dexterity.