Source: Tome of Magic
You can cast mysteries to maximum effect.
Prerequisite: Any two metashadow feats.
Benefit: Once per day, all variable, numeric effects of a mystery modified by this feat are maximized. This functions in most respects as the Maximize Spell feat.
Casting a maximized mystery is a full-round action.
Special: You can take this feat up to four times. To take it a second time, you must have five metashadow feats. To take it a third time, you must have eight metashadow feats. To take it a fourth time, you must have eleven metashadow feats.