Source: Tome of Magic
You can cast a mystery with a moment's thought.
Prerequisite: Any three metashadow feats.
Benefit: Once per day, you can cast a mystery as a swift action. This feat functions in most respects as the Quicken Spell feat.
Special: You can take this feat up to three times. To take it a second time, you must have seven metashadow feats. To take it a third time, you must have eleven metashadow feats.