Benefit: Pick one spell when you choose this trait. When you apply metamagic feats to this spell that add at least 1 level to the spell, treat its actual level as 1 lower for determining the spell's final adjusted level.
Ok, so if a metamagic feat adds one lvl, Magical Lineage will reduce one lvl.
So Shocking Grasp will still be a 1st lvl spell if using Metamagic +1lvl.
But I still don't understand why this is so great. Can anyone explain why this will benefit my magus?