In the event that a Balor hits a wizard with its lightning blade attack, can the wizard cast shield to attempt to turn the hit into a miss?

Quote from TexasDevin >>

In the event that a Balor hits a wizard with its lightning blade attack, can the wizard cast shield to attempt to turn the hit into a miss?

Yes. The trigger for the Shield spell's reaction is being hit by an attack roll, so it happens immediately after that, but before any effects of the hit are applied. That includes both damage and other non-damaging effects, such as the loss of reactions caused by that monster's attack.

If it didn't work this way, then the spell would be largely useless, because it wouldn't be able to prevent you from taking damage from attacks.

It is also true of some other reactions that increase AC such as the parry feature from the Defensive Duelist Feat and also true of Shield's ability to nullify magic missile.

The timing is found in the Reaction description but not in the Rule Glossary itself. 

Case where one triggers upon being hit and grant AC bonus can indeed turn a hit into a miss.

Reaction: In terms of timing, a Reaction takes place immediately after its trigger unless the Reaction’s description says otherwise.

Shield is also used as an example in Chapter 1:

As wagnarokkr explained, we can see where Shield interrupt the hit before damage and effect are applied within Making an Attack sturcture:

Resolve the Attack. Make the attack roll, as detailed earlier in this chapter. On a hit, you roll damage unless the particular attack has rules that specify otherwise. Some attacks cause special effects in addition to or instead of damage.

Thanks for the explanation. It appears the consensus is that the shield spell happens before the ability to react is lost rather than happening after the fact and turning back the clock, so to speak.

It was pointed out to me that the trigger for shield is the attack roll, not the attack itself. That handles my question perfectly.

Yeah Shield is a retcon spell. In all logic, you should cast it before the attack roll is made, but the rules say otherwise, so instead the dynamic goes like:
DM: the enemy attacks, you get hit.
PC: no I didn't.
DM: *rewinds time* the enemy attacks, you don't get hit.

The more I think about this, the more obvious the answer was from the beginning. This is no different that being at 1 hit point and getting hit with an attack. We would all agree you can still cast shield in that situation even though the hit would knock you unconscious and make you unable to take a reaction.

Quote from Natrel >>

Yeah Shield is a retcon spell. In all logic, you should cast it before the attack roll is made, but the rules say otherwise, so instead the dynamic goes like:
DM: the enemy attacks, you get hit.
PC: no I didn't.
DM: *rewinds time* the enemy attacks, you don't get hit.

I always see it more as:

DM: The enemy attacks. You're going to get hit (damage/effects not yet resolved)
PC: No I don't (casts Shield)

I don't see Shield  so much as a rewind time but as a recalculation to determine if the attack roll still equals or exceeds the target’s AC +5.

And when targeted by Magic Missile taking no damage as any darts strike you.