Shield of Reflection Confusion

[Cloudgatherer]

From the SRD:
Reflection

This shield seems like a mirror. Its surface is completely reflective. Once per day as a free action, it can be called on to reflect a spell back at its caster exactly like the spell turning spell.

Caster Level: 14th; Prerequisites: Craft Magic Arms and Armor, spell turning; Market Price: +5 bonus.

Would someone explain how this works to me? I'm assuming the use of "free action" is misleading, and it should be "not an action", otherwise what's the point?!?!

Also, when does one decide to reflect it? Can I decide to reflect after I fail my save? After I take damage? Before something?

I could make some stuff up (and is probably as valid), but any insight would be great.....

 

[Crothian]

You would decided to reflect it before any saving throw and before any damage dice are rolled.

 

[Cloudgatherer]

That could really bite though...guess I'll need some sort of spellcraft to determine what the heck I'm being hit with....

 

[Kae'Yoss]

Would someone explain how this works to me? I'm assuming the use of "free action" is misleading, and it should be "not an action", otherwise what's the point?!?!

Yea, I think it's rather a reaction than an action. Or maybe we're supposed to ready a free action (as a free action) to reflect a spell when it's cast at us. Of course, you'd to that all the time, and we're back at the reaction statement....