Immediate Interrupt Defensive Actions

[Mobius]

Immediate interrupt defensive actions, such as casting the Shield spell which grants +4 to AC and REF or the Staff of Defense class feature which grants CON mod for one attack to any defenses (this feature can be used even after the DM has declared the total damage).

So here's the question: should a player know what his/her DM's attack roll is before deciding whether or not to use the power?

Or should the DM choose not to declare the attack roll and player has to take a gamble and risk wasting the power? (attack roll is still higher even after addition.)

Nothing in the PHB addresses this.

I've read the D & D forums and some DMs have declared that they have no problems letting their players use their powers only when it is useful.

Realistically speaking, PCs may have a split second to determine if they can defend against an attack and react accordingly.

DM, what's your take?

[thedungeonmaster]

I have read the details on the Shield encounter power and also on the immediate interrupt rules on pg. 268 of the PHB.

The trigger for the Shield would require the wizard to be hit by an attack. If the attack misses, it is not a trigger.

Therefore, the wizard would know if the attack hits him or not. Precisely, the wizard is hit, he gets to use his immediate interrupt which is the Shield. The Shield interrupts the attack that hit by adding a +4 bonus to AC and Reflex until end of next turn.

But, the catch here is, the wizard will not know what score the monster rolled and the dmg dealt. Therefore, in my point of view, the wizard can know if the hit is successful before using shield. But, he does not know the die roll and the dmg incurred.

[Mobius]

For the Staff of Defense wizard class feature, it specifically states that the power can be used even after the DM had announced the damage.

So for Shield it is set just as the way you described.

[thedungeonmaster]

Yup, I know about the Staff of Defense. Read that part.