It supposedly works like the Spell Refection Magus Arcans, which IT says it is like the Spell Turning spell.
However Spell Turning does not work on Area of Effect or Range Touch Attack (RTA) spells. So which Elemental spells are I being protected from exactly?
So...Is it only unique spells of the Elemental subtype that target a single person without a RTA and Melee touch elemental attacks? (Watch out for that Spark Spell!)
If it does work that way only, that is a severely limited power to take. Regardless of the potential help it "might" do, why spend a limited Magus Arcana choice at 12th level on this, especialy when there are more useful and powerful Arcana you can take instead (IMHO).
Personally I would like to see if this was originally meant to work against Elemental RTAs? That would make more sense, but would take an official Errata.