Magical Lineage
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?
Best Answer
It's not really that great. When it first came out it was excellent because, unlike other metamagic level reduction sources, it didn't prevent you from reducing the level of a spell below it's starting point. For example with Metamagic Master (the best thing for a solo-spell metamagic build ever) or any other level lowering ability and Intensify Spell you could make Intensified Burning Hands a 0 level spell with Magical Lineage, which is pretty awesome.
Unfortunately Magical Lineage got errataed via the FAQ and this no longer works, so it's only useful in conjunction with other abilities that do allow this (like Metamagic Master), which makes it very limited in utility.