There is a Legacy version
here.
Melodious Spell [one-action] Feat 4Bard Concentrate Spellshape Source Player Core pg. 103 2.0
You subtly weave your spellcasting into a performance. If the next action you use is to
Cast a Spell, the spell gains the
subtle trait, hiding the shining runes, sparks of magic, and other manifestations that would usually give away your spellcasting. The trait hides only the spell’s spellcasting actions and manifestations, not its effects, so an observer might still see a ray streak out from you or see you vanish into thin air.
As part of using Melodious Spell, you can choose to
Create a Diversion,
Demoralize,
Perform, or
Request. If you do so, the spell you cast must have the
auditory,
emotion,
sonic, or
visual trait to gain the subtle trait.
Traits
Concentrate: An action with this trait requires a degree of mental concentration and discipline.
Spellshape: Actions with the spellshape trait tweak the properties of your spells. You must use a spellshape action directly before casting the spell you want to alter. If you use any action (including free actions and reactions) other than casting a spell directly after, you waste the benefits of the spellshape action. The benefit is also lost if your turn ends before you cast the spell. Any additional effects added by a spellshape action are part of the spell's effect, not of the spellshape action itself.