Do I add the bonus to my previous modifier or do I exchange my previous modifier for it when I use spells like Pass Without Trace?

Question

Pass Without Trace gives the player a +10 bonus to stealth checks. Would I add 10 to my initial stealth modifier or swap it for +10?

If I had a +2 stealth mod and use the spell would I have +12 or +10?

Answer 1

You have +12

It's a bonus, and generally, bonuses stack, so you add it to your current Dexterity (Stealth) modifier. Much like how you add your Proficiency bonus to your Dexterity (stealth) modifier if you are proficient in stealth.