Prerequisite: Requires a minimum of 13 Intelligence
As an Acolyte - spell casting became a metamagic feat for that caster, allowing them to increased the time a spell lasted, using a spell slot, of equal level.
If casting a spell, prolonged that spell to double its original duration. This requires a Short Rest.
Or when casting a Spell that requires both Verbal, or Somatic components, you can drop, and cast the spell using no gestures, or noise. This requires a Long Rest.
This feat requires the spell caster, to be level 6.