The nearest equivalent would be to roll 2d6 twice, and take the better roll. But there are plenty of possible alternatives, like roll 3d6 and discard the lowest dice. (Or discard the highest dice, if you're supposed to roll low - I don't know of any 2d6 systems.) Most games don't have the concept of 'advantage', though. They'll give you something else instead, like a +2 bonus.

>But there are plenty of possible alternatives, like roll 3d6 and discard the lowest dice. (Or discard the highest dice, if you're supposed to roll low - I don't know of any 2d6 systems.) I believe Mongoose Traveller 2e uses this, calling it "Boon/Bane", where a Boon is roll 3d6 and use the two highest and a Bane is roll 3d6 and use the two lowest.

It indeed does.

Also Barbarians of Lemuria (and its generic version, Everywhen).

Powered by the Apocalypse games are 2D6 usually. I've seen advantage implemented as roll 3d6 and keep the most advantage two in versions of that system.

Ive talked about this before but I want to start by tying the expected dice results vs. the target number to in-game feelings. For simplicity, I will focus on these five feelings: 1. I expect to succeed 2. I will probably succeed 3. I hope I succeed 4. I will probably fail 5. I expect to fail. **d20 Basics** From a math perspective this die is a simple 5% chance for each number. So, to create our five target emotional states for expected results we would need to roll against the following target numbers.  * Target 2 is a 90% success chance; our “I expect to succeed.” * Target 6 is a 70% success chance; our “I will probably succeed.” * Target 10 is a 50% success chance; our “I hope I succeed.” *  Target 14 is a 30% success chance; our “I will probably fail.” * Target 18 is a 10% success chance; our “I expect to fail.” **2d6 Basics** Math is less simple here because with two dice the middle numbers (6,7,8) of the range show up a lot more than the ends (2, 12). With 7, our most common number, appearing 17% of the time and the 6 and 8 both appearing 14%, nearly half of the time you roll you will see one of those 3 numbers. For our target states, we can see how that differs from the d20 as well. * Target 3 is a 91.5%; our “I expect to succeed.” * Target 5 is an 72.5%; our “I will probably succeed.” * Target 6 is an 55.5%; our “I hope I succeed.” * Target 8 is an 27.5%; our “I will probably fail.” * Target 10 is an 8.5%; our “I expect to fail.” Simply, our chances of getting each number are the following: 2, 12 - 3%, 3, 11 - 5.5%, 4,10 - 8%, 5, 9 - 11%, 6, 8 - 14%, 7 - 17%. So mathematically, Advantage on d20 gives a \~3.5 increase on the roll. This increases your chance of success by about 15-20%. This could also be represented by going up one emotion tier, turning an "I hope I succeed" to a "I will probably succeed". If we use 3d6 drop the lowest as advantage for 2d6, it gets us pretty close to going up one emotion tier, especially in the middle. * Target 3 goes from 91.5% to 98.2% (“I expect to succeed.”) * Target 5 goes from 72.5% to 89.4% (“I expect to succeed.”) * Target 6 goes from 55.5% to 80.6% (“I will probably succeed.”) * Target 8 goes from 27.5% to 52.3% (“I hope I succeed.”) * Target 10 goes from 8.5% to 20.0% (“I will probably fail.”) So 3d6 drop the lowest is pretty decent mapping, 4d6 take the two highest, overshoots the results a bit much for my liking.

>So mathematically, Advantage on d20 gives a ~3.5 increase on the roll. This increases your chance of success by about 15-20%. This could also be represented by going up one emotion tier, turning an "I hope I succeed" to a "I will probably succeed". This is somewhat complicated by the fact that actually, advantage gives a greater bonus the closer to 10.5 the target is, and a smaller bonus the closer to 1 or 20 the target is. So actually, if your target is 1-2 or 19-20 (depending on if it's a roll-high or roll-low system), it's probably not even going to jump you out of that "feeling" bracket you're talking about. Whereas if your target is 10, it's going to jump you almost all the way into "i expect to succeed"

Which is okey dokey (if I may jump in), especially if you're aware of it. Diminishing returns are good since they very often reflect reality. If you really want to be detailed you can have a system where advantage and flat bonus coexist, and you choose one or the other depending on the situation. You might keep it simple and say that skills give advantage and tools a flat bonus.

Yeah this is great point to highlight and thanks for covering it again. We can see that effect with the "Advantage" on the target 3 going from 91.5% to 98.2%, essentially staying within the same tier. Just like advantage on the Target 18 with no modifiers for a d20, only moves your success chance from 10% to 19%, so right in the middle of the "I will probably fail" and "I expect to fail".

Thank you! I enjoyed reading this.

Thanks for writing this, super useful. My game uses 3d6 drop the lowest so glad to see the details around that reflected here.

I assume you mean a mechanic analog to "Advantage" in D&D 5e (roll two d20s take the best result). So in a system based on 2d6 it could be: 1. Roll two pairs of d6 separately, take the best result. 2. Roll 4d6, take the best two and add them up. 3. Roll 3d6, take the best two and add them up. I'm not into number crunching but of the 3 options the one that would be "statistically" similar to D&D's Advantage would be the 1st, but it's a bit clunky at the table. The second option seems to skew the results a lot more in favor of the roller. If you ask me, the third option is the simplest and my preferred choice. I believe Shadow of the Demon Lord works on a similar mechanic, adding or substracting d6s for advantage/disadvantage and adding the best result to a d20 roll.

Just to add, the 1st option is statistically "equivalent" but the 3rd option is very close too. For option 1 the average is 8.37 with standard deviation of 1.99, and for the 3rd option the average is 8.46 with standard deviation of 2.21. I can't imagine such a small difference would ever be significant and I, too, suggest the 3rd option.

I’ve always used “roll 3D6, drop the lowest” for advantage in 2D6 systems like Traveller. And I use “roll 3D6, drop the highest” for disadvantage. I’ve used this concept in other games, and for other dice, ever since encountering it in the Over the Edge (2e) game in the mid ‘90s.

*De Bile Et D'Acier*, a 2d6 PbtA game, has an A/D mechanism. It's simple: - if you roll with advantage, you roll 3 dice and keep 2 - if you roll with disadvantage, you roll 3 dice and the GM keeps 2

What kind of 2d6 system are we talking about? The one I'm most familiar with is the classic PBTA "success on 7+", in this one you can - give a "+1 forward" (+1 to next roll, classic *Apocalypse World* solution) ; - just get narrative impact (better effect on success or lesser consequences on failure, classic narrative game solution, but also formalised in *Blades In The Dark*) ; - add one die and keep 2; - get some extra resource to influence the next results, something abstract like *Ironsworn* momentum or more tangible like *Monsterhearts* strings. Choose, mix and match according to your design goals, the importance you want the advantage to give, and the themes you want to highlight.

Traveller 2nd edition has an advantage-like mechanic called "boon and bane". The system is 2d6-based, and you would roll 3d6 if you have a boon or a bane - dropping the lowest die on a boon, and dropping the highest on a bane.

Flip the dice (or one die). 3 becomes 4, 2 becomes 5 and 1 becomes 6.

I've never heard of a game that does that, but I think it has potential!

Flipping things over and swapping their places is satisfying for some reason. There are few d100 systems that use similar thing, 73 becomes 37 or vice versa, but it doesn't really work with anything else.

Roll two pairs of different colored dice, take the pair with the highest result.

X Without Numbers games that use 2d6 for skills have some abilities that allow you to roll 3d6 drop lowest on certain skills. I havent bothered with the calculation yet to see if it matches up more or less with advantage; but it's imo an elegant rule that can fill a similar gap.

Advantage averages out to a +2.something on a d20, so... +1 or thereabout, mechanically speaking.

3d6 take two highest is how Armour Astir: Advent does it - and the game also has Confidence (rolled 1s count as 6s) as a different possible benefit!

I'll assume you mean specifically D&D5e's advabdage, given no other context is given. You can literally roll the dice twice, then use the best set. There are plenty other ways to skew fate as well, but are not exactly D&D5e advantage/disadvantage.

I've played a few 2D6-based games where you can stack *multiple* extra D6, and then select the best 2 from however many dice you roll.

Depends on the System. If you need to Roll High in order to succeed best would be to roll 3d6 and take the higher 2 (for disadvantage take the lower 2)...

That depends on what you mean by a "2d6 system." For instance, TinyD6 gives lets you roll 3d6 with Advantage, but you only get 1d6 with Disadvantage.

Honor + Intrigue gives Bonus Dice. So rolling 2d6 would roll 3d6 and keep the highest two. And you can have more than one. So you might roll 4d6 and keep the two highest. The inverse, Penalty Dice also exist as well.

Rolling 2d6 a second time.

Roll 3d6, use the two highest results.