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Using Advantage/Disadvantage Mechanic in Classic and Mongoose Traveller

I like the Advantage/Disadvantage used in D&D Next and in some other systems.

This is how it would work for Classic or Mongoose Traveller: if you had a situation where you have an advantage, instead of getting a static DM, you'd roll 3d6. If you have Advantage, you use the higher of the two dice to determine your results. If you have Disadvantage, you use the two lowest dice to determine your results.

I am thinking about importing this into Classic and Mongoose Traveller, but I'd like to get feedback on this, and especially thoughts about the average benefit/bonus when you have 'Advantage'.

Why might you use this instead of flat DMs?

The way Advantage/Disadvantage works is that you don't have to track a ton of DMs. If you have both advantage and disadvantage on the same dice roll, they cancel each other out and you don't roll the extra die. This rule applies even if you have multiple sources of advantage and disadvantage. For example, if two conditions you give an advantage, and another condition gives you disadvantage, they cancel each other out and you don't roll the extra die.

Having played D&D Next for over a year with this mechanic, I can tell you from experience that, at least in a d20 system, this makes things very simple at the table and helps reduce situations where a forgotten Dice Modifier goes unused but is later recalled (which often results in forcing a retcon or a dissatisfied player (this assumes your DMs are largely public; I know many don't play this way though)). Also, as a Gamemaster, this helps me from keeping track of so much math.

Thoughts?
 
Here are some articles on the math in a d20 system, in case you're wondering. I'm not seeing an easy way to map this to 2d6 probabilities, but love if anyone can decipher the math on importing such a Advantage/Disadvantage mechanic in Traveller. :)

http://rpg.stackexchange.com/questions/14690/how-does-rolling-two-dice-and-taking-the-highest-affect-the-average-outcome

http://www.critical-hits.com/blog/2012/06/11/dd-advantage-vs-flat-bonuses/

http://onlinedungeonmaster.com/2012/05/24/advantage-and-disadvantage-in-dd-next-the-math/
 
It sounds like a simple way to implement advantages and disadvantages. I would have to try it out to see if it worked in practice, but at first glance it looks good.

How would you assign advantages and disadvantages? Do each player choose one of each from a list, or do they get points to buy advantages by taking disadvangages? Do they all cost the same or are some worth more, perhaps based on how likely they are to come up in a game session?


Hans
 
This in my mind is a GM controlled mechanic.

GM: "You're intoxicated, so now that you're in a bar fight, roll with Disadvantage." (player rolls 3d6, uses lowest 2 dice).

<later>

GM: "Now you're knocked down on the floor of the bar, and still intoxicated. Roll your attack with Disadvantage."

<a moment later>

GM: "Your friends are laying down suppressing fire, giving you and Advantage. But you're still prone and intoxicated. The Advantage and Disadvantage cancel each out out. Roll 2d6."​

Minimizes the math, and reduces GM fiat in determining Dice Modifiers.

The only question I have is -- is the 3d6, take the lowest (or highest) way too much of a swing mathmatically?
 
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For 3d6 drop lowest you get
2: 0.46%
3: 1.39%
4: 3.24%
5: 5.56%
6: 8.79%
7: 12.50%
8: 15.74%
9: 16.67%
10: 15.74%
11: 12.50%
12: 7.41%

average = 8.46

For 2d6 it is
2: 2.8
3: 5.6
4: 8.3
5: 11.1
6: 13.9
7: 16.7
8: 13.9
9: 11.1
10: 8.3
11: 5.6
12: 2.8

average = 7

Disclaimer: data from internet
 
Thanks @CosmicGamer!

Looks like you have a bonus of around 2-3 for most scores. Advantages results would still be in the 2-12 (skewing to the higher end) vs. 4-14 results in the case of a +2 DM for example.

So far, I still like the Advantage/Disadvantage idea.
 
It sounds like a simple way to implement advantages and disadvantages. I would have to try it out to see if it worked in practice, but at first glance it looks good.

How would you assign advantages and disadvantages? Do each player choose one of each from a list, or do they get points to buy advantages by taking disadvangages? Do they all cost the same or are some worth more, perhaps based on how likely they are to come up in a game session?


Hans
The way you have construed that is entirely wrong, Hans.

it is a die roll modifier replacement. If the adjusted DMs would be in player favor, roll in advantage mode; if it would be -2 or worse, disadvantage mode.
 
The way you have construed that is entirely wrong, Hans.
Too bad. It sounded like an excellent way to introduce advantages and disadvantages. If I was going to run a Traveller campaign soon and if I wasn't going to use my own rules, I'd definitely look into it.


Hans
 
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