From Compendium of Worldly Lore
Needs review
Source: Dungeon Master's Guide
Description: You can cast spells using metamagic feats more easily than normal.
Prerequisites: Spellcraft (30 ranks), Four Metamagic Feats
The spell slot you must use to cast a metamagic spell is one level lower than normal (to a minimum of one level higher than normal). For instance, you could cast a quickened spell as a spell of three levels higher than normal rather than four levels higher. This feat has no effect on a metamagic feat that requires a spell slot one level higher than normal or does not require a higher level slot.
Special
You can gain this feat multiple times. The effects stack, though you can't lower the level of any metamagic spell's slot to less than one level higher than normal.