This card allows me to put an enemy with which I'm engaged back into staging area.

Here's the question: if I play this event during an enemy's attack, but before the damage is resolved, what will happen? For example, I turn a shadow card face-up and I don't like what I see, so I play "A Light in the Dark" to get rid of the enemy till the next round. Will that work and cancel the attack, or the enemy will deal damage anyway, even though it's in the staging area now?

Couldn't find the answer in any FAQs.

This hasn't been officially addressed in the FAQ, but there is a similar situation that answers the question (barring an official clarification from FFG).

In a two-player game, if an enemy is engaged with your partner, you can Sneak Attack Son of Arnor into play during that enemy's attack (i.e. after the shadow card is revealed, before attack damage is actually calculated). If you then trigger Son of Arnor's response to engage the enemy, the attack will continue against YOU instead of against your partner.

The more general principle in this example--the one that applies to your question--is that enemy attacks only continue against the original defender as long as the enemy remains engaged with that player. So, if you send an enemy back to the staging area before it deals damage, the attack will end before damage is dealt.

Until FFG rules otherwise, that is the interpretation most consistent with existing rules precedent.

Thanks for the answer, that's exactly how I thought!

One thing to keep in mind, the shadow card resolves before you have a chance to play actions. So if the shadow card destroys an attachment, kills an ally, does direct damage to a character or summons another monster, etc, you can not escape the effect.

Bohemond said:

Very true. It's usually safest to play A Light in the Dark before the enemy attacks, thereby avoiding any problematic shadow effects.