Wednesday, May 27, 2015

Just-in-Time Durations

So the player fails their save vs paralysis.  Now, they're paralyzed for 1d6 rounds.  The DM rolls a d6 and gets a '5'.  He tells the player "You're paralyzed." and makes a note on his tracking sheet.  Five rounds later, he'll tell the player "You're no longer paralyzed.  What do you want to do?"

That's how it's always been done.

art by KD Stanton
So, I've already written about why I think just-in-time-resolution is better (where the effect isn't resolved until it actually matters).  In this case, the player just goes into paralysis and the duration of the paralysis isn't resolved (and no know knows the duration) until the paralysis effect expires.

This requires a dice trick.  It only works if the duration is determined by a single roll of the dice.  (So, it doesn't work for 2d6, but it works for 1d8+1.) 
  1. The first turn it might wear off, roll a dWhatever-the-size-of-the-die-was.  So if it lasts for 1d4 rounds, you'd roll a d4.
  2. If get a 1 on the dWhatever, the condition wears off and you can act normally.
  3. If the condition doesn't wear off, at the start of your next turn, roll a dWhatever-1.  If you get a 1, the effect wears off.  Otherwise, continue this process of decreasing the die size.
I know it looks weird, but its mathematically identical to a duration of 1d6 turns.  Here's an example.

DM: You're paralyzed.
Player: Fuck.
Player's 1st Turn: *character is paralyzed.*
Player's 2nd Turn: Rolls a d6, gets a 2.  Character is still paralyzed.
Player's 3rd Turn: Rolls a d5, gets a 5.  Character is still paralyzed.
Player's 4th Turn: Rolls a d4, gets a 1!  Character is no longer paralyzed, and takes their turn as normal.  Everyone at the table was excited and surprised!  The player saves the day!  Yay!

Yes, if they end up rolling a d2 and getting a 2, the surprise is ruined, and they know it'll wear off next round.

Yes, you might not have a d5.  Just use a d10, or a d6-reroll-any-sixes.

Using Just-in-Time Durations has a few advantages:

DM doesn't forget.  
It's (hopefully) rare, but sometimes the DM just forgets to tell the character that they're no longer paralyzed after 5 rounds, and the poor character stays paralyzed until someone asks the DM how much longer the paralysis is going to last.  It's shitty, but when there are a million things to keep track of, sometimes the DM loses track.

DM doesn't metagame.
Two of the players are paralyzed by ghouls.  The DM rolls a pair of d6s, and. . . shit.  Both of the players are paralyzed for 6 rounds each.  They might get a TPK here.  And then the idea creeeeeps into the DM's head: "Maybe I should reduce the ghoul's HP, or start fudging their attack rolls, or. . ."  If you are a DM who wants to be free from temptation, this is one solution.

Player has something to do.
I think this is what 4e was going for when it made all of those "55% chance to expire each turn" effects.  Players like rolling dice, even when their character is paralyzed.  Especially when their character is paralyzed.  It puts the roll back in their hands, too, so if they get TPK'd, they can own the results.

Players have an idea of how bad it is.
I like giving players more information.  That's how they make informed decisions.  For example, I'll usually tell you a creature's AC after you attack it once.  The same goes for durations.  Once a player finds out that the hallucinations last 1d6 minutes, they might decide to retreat from combat.  But if they find out that the hallucinations last 1d6 rounds, they might decide to stay in combat to tough it out.  Let players know the risks, so that they'll have no one else to blame when they fail.

Dice rolls are out in the open.
Everyone likes this, right?

So there you have it.

You can also use this mechanic for Just-in-Time Charges.  You start rolling duration on the first turn that an effect might wear off (the beginning of the second round of the effect), so you do the same thing with a wand with an unknown 

Players find a wand with 1d20 charges?  You could keep track of its charges on your sloppy pigpen of a DM's sheet* while you wait for them to identify it, OR
  1. Player uses the wand and you tell them that it has 1d20 charges.
  2. The next time they use it, they roll a d20.  
    1. If they roll a 1, it fizzles.
    2. If they don't roll a 1, it becomes a wand with 1d19 charges.
  3. The next time they use it, they roll a d19.
  4. Etc.
Wands in my game have 0-19 charges (d20-1), so my players start rolling that d20 the first time they use a wand.  It's always possible that they picked up a wand with no charges. 

*at least mine is a sloppy pigpen.  Your DM sheet may be more of a duck pond.  I don't judge.


  1. I'm just amazed that the probabilities are the same!

  2. Would it work the same way doing this:
    DM: You're paralyzed.
    Player: Fuck.
    Player's 1st Turn: *character is paralyzed.*
    Player's 2nd Turn: Rolls a d6, gets a 2. Character is still paralyzed.
    Player's 3rd Turn: Rolls a d6-1, gets a 5(4). Character is still paralyzed.
    Player's 4th Turn: Rolls a d6-2, gets a 3(1)! Character is no longer paralyzed, and takes their turn as normal.

  3. I ain't no statistician, but wouldn't rolling 1d6-1 rather than 1d5 give you a 2-in-6 chance (assuming you're looking for a result of 1 or less) rather than the 1-in-5 chance you're looking for?

    1. Yeah. The probability across the five dice rolls are

      1/6 = 17%
      1/5 = 20%
      1/4 = 25%
      1/3 = 33%
      1/2 = 50%


      1/6 = 17%
      2/6 = 33%
      3/6 = 50%
      4/6 = 67%
      5/6 = 83%

      So while the first method has a 17% chance of terminating on the 6th round, as you'd expect, the second method has only a 1.5% chance, which is surprisingly small.

  4. Yoinked! Will be using this system for paralysis/other player conditions from now on. I use something similar for powerful magic weapons like wands, but I hate tracking so player rolls a d4 (very powerful) d6 (normal) or d8 (weak item) and on a 1 the item is out of power. There is a nice tension between players preserving these items and possibly dying or surviving but losing a neat magical item.