Several features like the Lucky feat, the divination school, and bardic inspiration can change the outcome of a roll by adding or changing the result.

The lucky feat states:

You can choose to spend one of your luck points after you roll the die, but before the outcome is determined.

The divination school states:

You can replace any attack roll, saving throw, or ability check made by you or a creature that you can see with one of these foretelling rolls. You must choose to do so before the roll, and you can replace a roll in this way only once per turn.

And the bardic inspiration states:

The creature can wait until after it rolls the d20 before deciding to use the Bardic Inspiration die, but must decide before the DM says whether the roll succeeds ar fails.

My issue is understanding the concept "Before the outcome is determined". Some examples:

  • Bob rolls a 1 on an attack roll, the outcome is automatically determined, he failed. He can't roll a luck dice, because 1 is a natural failure for an attack.

  • Tim the ogre attacks Bob, and rolls a 20 on the dice. It's a critical and automatic succes. Bob can't spend a luck dice to change Tim's roll, because a 20 is a natural succes.

Bardic inspiration is out of the formula, because modifiers don't change the outcome of an automatic succes or failure.

In the case of the divination school Bob the Wizard can expend those dice when the GM says "the ogre attacks you", Or when Bob decides to attack and choose a foretelling dice.

My question is. Did I get everything right, or I missed something? And, What happens with the divination school feature when you roll behind the DM screen?

Thanks for your answers, and sorry for my english, It isn't my native language.

  • 1
    \$\begingroup\$ Possible duplicate of When exactly is an outcome determined? \$\endgroup\$
    – HellSaint
    Commented May 29, 2018 at 14:22
  • \$\begingroup\$ Although the duplicate is actually opposite (I couldn't find this question when I wrote my own, my bad), I'm voting this as the dupe because Vigil's answer is generally more complete and actually quotes the rulebooks for them. If needed I can create a meta question, but first I'd like to be sure these are indeed dupes (seem like it for me, and I'm the one making the other question, soo....) \$\endgroup\$
    – HellSaint
    Commented May 29, 2018 at 14:25
  • \$\begingroup\$ I've Gone and done so as there are 4 such questions, 2 from today alone. \$\endgroup\$
    – Jason_c_o
    Commented May 29, 2018 at 15:05
  • 2
    \$\begingroup\$ Until the Meta is resolved, I'm refraining from voting to close. \$\endgroup\$
    – Jason_c_o
    Commented May 29, 2018 at 15:06

3 Answers 3


The result of a roll is not determined until the DM says what the result is, even in the case of a 1 or 20. There are cases, such as attacking an illusion or something immune to that damage type, wherein the DM lets the player roll just to hear the dice clatter.


My interpretation is that you can change also rolls of 1 or 20, but not after the DM has narrated the results of your action.

So in case 1, Bob can use his "Lucky" feat to re-roll a failure. And in case 2, he can use it to turn a hit into a miss - but only before he knows how much damage that hit is going to inflict. You cannot wait with your luckyness until it is confirmed that the hit would kill you.

For bardic inspiration (or other things that add dice to a d20 roll, like "Blessing"), the 1 on the d20 still is a failure, no matter how large the bonus.

  • \$\begingroup\$ On Page 167 of the PhB, under Lucky states "You can also spend one luck point when an attack roll is made against you. Roll a D20, and then choose wether the attack uses the attacker's roll or yours." \$\endgroup\$
    – Trolleitor
    Commented Oct 12, 2015 at 15:53
  • 1
    \$\begingroup\$ @Escroteitor I stand corrected. I adapted my answer, but the idea is still the same. Rerolls should work for crits, too. \$\endgroup\$
    – Neuneck
    Commented Oct 12, 2015 at 16:04

"Before the outcome is determined" indicates prior to when the GM communicates that you've either succeeded or failed your roll. If you rolled a 5 and believe that you'd fail a will save for example, before the GM tells you that you've failed your save you can use the listed abilities to change the outcome of the roll. This applies to any roll, 1 or 20. Saves, Attack rolls, skill checks. They can all utilize the luck or foresight that comes from divination, lucky, or Bardiac Inspiration.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .