Can a player ask if an immediate interrupt blinding attack will force a miss?

Question

I believe that when a Wizard uses Staff of Defense or Shield, which are both immediate interrupts, she may ask the DM if the power will prevent the attack from connecting.

Does the same hold true when the immediate interrupt affects an enemy, rather than simply protecting an ally?

A player in our group has a Runepriest with the following power:

Word of Blinding Shield
Encounter Immediate Interrupt
Trigger: An enemy makes an attack roll against an ally.
Hit: target is blinded until the end of it's turn.

Would it be reasonable for the player to ask the DM if this power would cause the original attack to miss?

Is this all based on a misunderstanding of immediate interrupts?

Answer 1

Technically the DM is not required to tell players whether an immediate interrupt will cause a triggering attack to miss unless the interrupt explicitly says so. Players may be able to figure it out on their own if they're allowed to see the DM's die rolls (some groups do this, some don't) and they've had a couple example attacks to estimate the monster's attack bonus from.

Note that Shield and Staff of Defense allow the player to find out whether the un-modified attack will hit or not before deciding to use them (Shield is triggered by a hit, and Staff of Defense explicitly says you can wait until you find out the damage total, which is even better), while Word of Blinding Shield does not (it's triggered by the attempt to hit).