D&D 5E Reactions

[Arial Black]

We have no reason to suppose that the two effects of being hit by shocking grasp happen at different times! They both happen (when you are hit), and both happen at the same time.

While we don't (initially) know how the reaction-denying effect interacts with Uncanny Dodge, we do know that UD happens before the damage, and since we know that the reaction-denial happens at the same time as the damage we can deduce that UD must happen before the reaction-denial.

 

[Hriston]

We have no reason to suppose that the two effects of being hit by shocking grasp happen at different times! They both happen (when you are hit), and both happen at the same time.

While we don't (initially) know how the reaction-denying effect interacts with Uncanny Dodge, we do know that UD happens before the damage, and since we know that the reaction-denial happens at the same time as the damage we can deduce that UD must happen before the reaction-denial.

We don't know that reaction denial happens at the same time damage is taken. All we can say is they both happen "on a hit". To me, that implies they are both generally simultaneous with the hit itself, but without any particular degree of precision.

Uncanny Dodge, on the other hand, is a reaction, so unless some particular timing is specified, the trigger completes before the reaction can be taken. In the case of Uncanny Dodge, the trigger is the hit. Once you've been hit, you could use Uncanny Dodge, except you were hit with shocking grasp, so you can't use any reactions.

 

[Dausuul]

Excellent all-round advice that I'm sure everyone here can agree with. Rules decisions for any individual game start and stop with the DM!

However, for any that have a nigh uncontrollable urge for an "official" ruling, here it is, courtesy of Jeremy Crawford:

"The hit of shocking grasp occurs before Uncanny Dodge, so yes, that spell prevents a use of Uncanny Dodge."

Link to the quoted tweet is below.

https://twitter.com/JeremyECrawford/status/717119902469885952

Hmm. Well, I don't think much of Crawford's reasoning, but I'll concede the point on the official rules (and then house-rule it the other way at my table).

 

[Arial Black]

We don't know that reaction denial happens at the same time damage is taken. All we can say is they both happen "on a hit". To me, that implies they are both generally simultaneous with the hit itself, but without any particular degree of precision.

Uncanny Dodge, on the other hand, is a reaction, so unless some particular timing is specified, the trigger completes before the reaction can be taken. In the case of Uncanny Dodge, the trigger is the hit. Once you've been hit, you could use Uncanny Dodge, except you were hit with shocking grasp, so you can't use any reactions.

'Being hit' and the effects of being hit are different things in the game rules.

For this spell, the effects of being hit are:-
* damage
* reaction-denial

Uncanny Dodge triggers, as you say, upon 'being hit', and would therefore happen before the effects of being hit.

We know for a fact that this is true, because UD happens before one of the effects of being hit (the damage). Therefore, UD must happen after 'being hit' and before the effects of that hit are applied.

 

[Hriston]

Uncanny Dodge triggers, as you say, upon 'being hit', and would therefore happen before the effects of being hit.

That doesn't follow. The effects of being hit also trigger upon being hit. So you now have three things that trigger off the hit. Adjudicating how those three things interact must take into account reaction timing, what the reaction says it does, and what the spell says it does.

We know for a fact that this is true, because UD happens before one of the effects of being hit (the damage).

It happens before the damage is applied. The damage dice must be rolled before Uncanny Dodge can halve the damage, of course. You could say that Uncanny Dodge's timing interrupts damage taking. There's absolutely no reason to think it also interrupts reaction denial.

Therefore, UD must happen after 'being hit' and before the effects of that hit are applied.

I believe it's a mistake to associate the two effects that way. What you have is three things that follow from the hit. An order for them should be based on the guidelines for reaction timing, what the reaction says it does, and what the spell says it does.

 

[Uller]

This conversation is circular at this point. I'm firmly on the side of reactions that trigger on a hit modify the effects of the hit before the effcts are applied because that makes more sense to me and is easier to adjudicate. Edit: and others see it differently and thats fine...but it seems to me you either have to resign yourself to case by case judgments (again...fine...rule what's fun at the moment) or you get some results that, to me, don't line up with what one would expect.

I already gave the ghoul paralysis example...some have gone so far as to say that if you fail your save then you can't us UD or even Shield. That's fine if that's how you want to rule it. But to me Uncanny Dodge is....well...Uncanny. Shield happens before the blow lands and so does UD or any other reaction triggered "on a hit".

Another example...a trap that attacks anyone opening a chest with a beam of light...it makes a +5 attack and on a hit deals damage and blinds the target for a time...

Can you use UD to halve the damage? Or is the target blinded and therefore unable to see the attacker (the trap)?

 

[TheWriterFantastic™]

This:

It happens before the damage is applied. The damage dice must be rolled before Uncanny Dodge can halve the damage, of course. You could say that Uncanny Dodge's timing interrupts damage taking. There's absolutely no reason to think it also interrupts reaction denial.

I've bolded the key thing - Uncanny Dodge's timing interrupts damage.

Since the reaction interrupts (i.e. occurs prior to) the damage, it has to occur prior to the effects as well, since the effects either occur at the same time as damage, if not after damage, as indicated in Step 3 of Making an Attack in the Basic Rules and PHB.

The reaction doesn't postpone the timing of the damage, to cause it to occur later in the sequence -- if it actually postponed the damage after the effect, then I could see an argument for the effect negating the reaction, but since it must interrupt the damage event, it must interrupt any simultaneous or subsequent event. Note that it's not preventing the effect of Shocking Grasp, but just halving the damage.

Either way, the target is burning their reaction against the attack, having the desired effect of preventing further reactions until the target's next turn.

At 5th level, when Uncanny Dodge becomes available, a like leveled Shocking Grasp would cause 6 damage, on average, with Uncanny Dodge preventing an average of 3 damage -- considering RAF (Rules as Fun), it seems nitpicky to go to such an extreme ruling on RAW, where it's a stretch to rule that it doesn't occur before the damage (and effect), since the desired effect, using Shocking Grasp to prevent the target's meaningful use of a reaction, for say Counterspell or an opportunity attack.

I say let the player burn the reaction to reduce the 3 damage.

 

[Arial Black]

It happens before the damage is applied.

...AND before the reaction-denial is applied!

Both the damage AND the reaction-denial are effects of the spell that get applied when the rules say they do. We know that UD occurs before the damage gets applied, both are effects of the spell, therefore both get applied at the same time, after UD.

 

[Hriston]

...AND before the reaction-denial is applied!

No, it doesn't. Uncanny Dodge says nothing about interrupting reaction denial effects.

Both the damage AND the reaction-denial are effects of the spell that get applied when the rules say they do.

The spell says they apply upon being hit, yes?

We know that UD occurs before the damage gets applied, both are effects of the spell, therefore both get applied at the same time, after UD.

There's no reason to believe that. Uncanny Dodge has no power against the reaction denial effect.

 

[Hriston]

Another example...a trap that attacks anyone opening a chest with a beam of light...it makes a +5 attack and on a hit deals damage and blinds the target for a time...

Can you use UD to halve the damage? Or is the target blinded and therefore unable to see the attacker (the trap)?

First of all, this is a poorly designed trap. Its target should make a Dexterity saving throw to avoid its effects. But assuming the Rogue is in combat with the trap, and that the trap is hidden, the Rogue could not use Uncanny Dodge. This has nothing to do with the blinding effect.