Silent Performance (5e Feat)
From D&D Wiki
Prerequisites: Ability to cast at least 1 spell and play at least 1 instrument
As a magical caster and performer you've spent several hours practicing your craft to be as unique and useful as possible. This allows you to gain the following benefits:
-You gain proficiency in (Performance). If you are already proficient in the skill, you add double your proficiency bonus to checks you make with it.
-When casting a spell with a verbal component you may make a (Performance) check against viewers' passive (Perception). If you are successful they are unaware of a spell being cast and believe it is just a performance. If you succeed by 5 or more you can choose to have the performance be silent.