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Advantage vs Disadvantage in 5th Edition Dungeon and Dragons

When the 5th Edition of Dungeons and Dragons was released in 2014 they introduced a very important new part of the game: Advantage and Disadvantage, which replaced bonuses/minuses to hit / to succeed in various situations, which depends on the circumstances.

Advantage - The player rolls two d20 dice, and must use the better roll of the two.

Disadvantage - The player rolls two d20 dice, and must use the worst roll of the two.

However a lingering question remained, how much of an equivalent bonus or negative to hit / succeed is Advantage and Disadvantage?

To find out we need to do some fancy math involving odds, possibilities and calculate the correct average bonus/negative. And to make it easier for people to understand we have broken it down below, showing what you need to roll to get the points in difference, and the % chance of actually rolling that.

19 points difference (20/1), only 1 way to roll it. 0.48%
18 points difference (20/2, 19/1), only 2 ways to roll it. 0.95%
17 points difference (20/3, 19/2, 18/1), only 3 ways to roll it. 1.43%
16 points difference (20/4, 19/3, 18/2, 17/1), only 4 ways to roll it. 1.90%
15 points difference (20/5, 19/4, 18/3, 17/2, 16/1), only 5 ways to roll it. 2.38%
14 points difference (20/6, 19/5, 18/4, 17/3, 16/2, 15/1), only 6 ways to roll it. 2.86%
13 points difference (20/7, 19/6, 18/5, 17/4, 16/3, 15/2, 14/1), only 7 ways to roll it. 3.33%
12 points difference (20/8, 19/7, 18/6, 17/5, 16/4, 15/3, 14/2, 13/1), only 8 ways to roll it. 3.81%
11 points difference (20/9, 19/8, 18/7, 17/6, 16/5, 15/4, 14/3, 13/2, 12/1), only 9 ways to roll it. 4.29%
10 points difference (20/10, 19/9, 18/8, etc etc etc etc etc... 12/2, 11/1), only 10 ways to roll it. 4.76%
9 points difference (20/11, 19/10, 18/9, etc etc etc etc etc... 11/2, 10/1), only 11 ways to roll it. 5.24%
8 points difference (20/12, 19/11, 18/10, etc etc etc etc etc... 10/2, 9/1), only 12 ways to roll it. 5.71%
7 points difference (20/13, 19/12, 18/11, etc etc etc etc etc... 9/2, 8/1), only 13 ways to roll it. 6.19%
6 points difference (20/14, 19/13, 18/12, etc etc etc etc etc... 8/2, 7/1), only 14 ways to roll it. 6.67%
5 points difference (20/15, 19/14, 18/13, etc etc etc etc etc... 7/2, 6/1), only 15 ways to roll it. 7.14%
4 points difference (20/16, 19/15, 18/14, etc etc etc etc etc... 6/2, 5/1), only 16 ways to roll it. 7.62%
3 points difference (20/17, 19/16, 18/15, etc etc etc etc etc... 5/2, 4/1), only 17 ways to roll it. 8.10%
2 points difference (20/18, 19/17, 18/16, etc etc etc etc etc... 4/2, 3/1), only 18 ways to roll it. 8.57%
1 points difference (20/19, 19/18, 18/17, etc etc etc etc etc... 3/2, 2/1), only 19 ways to roll it. 9.05%
0 points difference (20/20, 19/19, 18/18, etc etc etc etc etc... 2/2, 1/1) , only 20 ways to roll it. 9.52%

If you add them up there are 210 possible different combos.

The % chance is calculated by dividing the number of possible rolls by 210, and converted to percentage, and rounded up/down to the nearest 0.00%. If you care to add up all the percentages, they add up to 100.00%.

Looking at the above chart what you realize is that the odds of you rolling a large difference like 18 points or 19 points is pretty rare, whereas rolling point differences that are between 0 and 6 are in comparison, quite common (there is a 56.67% chance of rolling a difference between 0 and 6).

So what is Advantage and Disadvantage on average?

Well the point differences are added up and the divided by the number of combos...

19 + 36 + 51 + 64 + 75 + 84 + 91 + 96 + 99 + 100 + 99 + 96 + 91 + 84 + 75 + 64 + 51 + 36 + 19 + 0 = 1330 points.

So 1330 points divided by the 210 combos = 6.333~

So Advantage is on average equal to +6.333. It improves your odds of success on a d20 by 31.667%.

And Disadvantage is on average equal to -6.333. It increases your odds of failure by 31.667%.

The results of the final number used by the player is also dramatically skewed. The chances of rolling a 15 or higher when you have Advantage is dramatically improved. And the reverse for Disadvantage.

Visit http://andrewgelman.com/2014/07/12/dnd-5e-advantage-disadvantage-probability/ to learn more.


Different DMs vs the Rules as Written (RAW)

In the rules there are various situations described when a character would get advantage or disadvantage. However DMs are also at their leisure to adjudicate various situations where they feel PCs / monsters also get advantage or disadvantage.

Because I like to make my own games fun and exciting I tend to be very liberal with advantage / disadvantage and when to apply either of them.

I also like to look at things logically. For example missile fire vs prone targets at medium to long distances, it does make sense that they should be at Disadvantage.

However if they are within point blank range (30 feet), I would argue they should actually have Advantage vs a prone target. And for those with the Sharpshooter feat, I would double the Point Blank distance to 60 feet. I base this on 28 years of archery experience and being a professional archery instructor. Why? Because I am a firm believer in adding more realism to combat.


As a DM, another thing I allow for is issues like higher ground, being on horseback, flanking, charging, etc. They sometimes get advantage, depending on the circumstances. In other circumstances I might only give a bonus to hit instead of Advantage... or I might give both if there is a combination of factors. Or the player might have a bonus to hit + Disadvantage, or worst of all - a negative and Disadvantage.

But I also like adding more obstacles, difficult terrain, slippery areas, flooded areas, caltrops, traps, mud, quicksand, collapsing ceiling, etc.

So it all balances out, but makes for exciting combat.

How does Advantage / Disadvantage compare to other Editions of Dungeons & Dragons?

Defender Sleeping or Held, Automatic Hit (and possibly Automatic Critical)
Defender Prone or Stunned, +4 to Hit
Charging, +2 to Hit
Flanking, +2 to Hit
Defender Off Balance, +2 to Hit
Defender is Surprised, +1 to Hit
Attacker on Horseback, +1 to Hit
Attacker on Higher Ground, +1 to Hit
Defender on Higher Ground, -1 to Hit
Defender on Horseback, -1 to Hit
Defender Invisible, -4 to Hit + 50% chance of a complete miss.

So having advantage or disadvantage is a big deal in 5th Edition. It is bigger than any other bonuses a person might have got from previous editions. Someone on horseback (+1) charging a person (+2) they are flanking (+2) only gives a total bonus of +5, and how often does that happen?

To get a +6 bonus to hit you would need to charge at someone who is prone. Again, very rare.

This emphasis on advantage / disadvantage is compound by the fact that characters don't get many bonuses to hit in 5th Edition.

In 3rd edition a 15th level fighter got +15 to hit (+1 per level of the fighter class).

In 2nd edition a 15th level fighter had a Thac0 that was 14 points lower (basically the equivalent of having +14 to hit).

But in 5th edition, a 15th level fighter gets a paltry +5 to hit from their proficiency bonus. That is it.

In 5th edition: Magical items are also maxed out at +3; Bonuses to Hit don't Stack, very few things provide a bonus to hit.

This is then offset by lower armour class ratings for both monsters and armour types, and even spells that provide an AC bonus have been reduced (eg. Mage Armour is AC 13 in 5th Edition, instead of 14 in 3rd Edition).

Thus having Advantage and trying to prevent yourself from having Disadvantage is extremely important in 5th Edition.

Advantage / Disadvantage and 5th Edition Feats

This means that certain combat oriented Feats are likewise important:
  • Alert - For defense against hidden attackers
  • Crossbow Expert - No disadvantage if using a crossbow against attackers who are 5 feet away.
  • Grappler - Advantage on all attack rolls against creatures you are grappling.
  • Lucky - 3 times per long rest, you can turn any roll, including Disadvantage rolls, into "Super Advantage" rolls where you choose which roll to use. So for example if you have Disadvantage because the target is long range, you spend a Luck point and instead of rolling twice and taking the worst roll, you roll 3 times and take the best roll. Hence why it is sometimes called "Super Advantage".
  • Mounted Combatant - When mounted you gain Advantage on rolls against non-mounted enemies. (I give this to all characters routinely, provided if they are effectively on higher ground.)
  • Sharpshooter - You don't get disadvantage vs targets at long range or targets with 50 to 75% cover. (The meme further above references 90% cover, which must be a house rule they are using.)
  • Spell Sniper - Similar to Sharpshooter, but for spells. Range attack spells ignore 50 to 75% cover.
This doesn't mean that there are not other Feats worth taking, but the above ones certainly are important within the context of 5th Edition's emphasis on Advantage / Disadvantage.

Advantage / Disadvantage and Different Classes

Various class skills can also provide Advantage on a regular basis, with Stealth being one of the easiest ways to gain Advantage.

Rogues for example can gain Advantage quite often since they can use Cunning Action to use Stealth as a bonus action. A rogue with a good Dexterity, a good Stealth, and Sharpshooter could get Advantage on a regular basis, and thus get Sneak Attack on a regular basis. Each round they could shoot their arrow and then use a Cunning Action to re-Stealth, potentially getting Stealth and Advantage almost every round. This is sometimes known as Cunning Stealth.

It makes me wish I had decided to play a Rogue instead of a Ranger for Adventurers' League. I might end up doing so yet, if I decide to later multi-class my ranger.

Clerics with the Divine Domain Trickery can also use Stealth regularly using Blessing of the Trickster (which gives Advantage on Stealth checks). The problem however is that they have to use an action to do it, because unlike Rogues, they cannot do it as a bonus action. A Cleric/Rogue thus makes a bit of sense, so that they can get both Blessing of the Trickster and Cunning Stealth.

Clerics using Bless and Bane can flip the favour of combat for most of the combat, giving allies +1d4 to hit and enemies -1d4. This then offsets or bolsters Advantage/Disadvantage.

Rangers can choose to get the spell "Pass without Trace" at 5th level, which provides +10 to Stealth checks to both them and nearby allies. Thus a Ranger/Rogue or even a Cleric/Ranger/Rogue holds potential to be an amazingly Stealthy killing machine.

Melee Fighters would be well advised to take up Tripping their opponents, as once tripped the fighter gains advantage on all attack rolls until their opponent stands back up. Using a Net is also handy to restrain enemies / give the fighter advantage temporarily. The Battle Master maneuver Trip Attack is a good way to accomplish this. (Please note that tripping deals both damage, and knocks the enemy prone, and once the enemy is prone other allies also gain Advantage.)

Ranged Fighters should try to bolster their Stealth, similar to rangers. Eldritch Knights for example have access to spells that would help accomplish this.

Spellslingers such as wizards and sorcerer's usually don't need to worry about Advantage or Disadvantage. One good Fireball usually does the trick.

Thus Advantage / Disadvantage is mostly a combat issue. While it is obviously handy to have for skill checks and saving throws, it happens less often and is usually less important.

1 comment:

  1. Wow...just ...Wow. Excellent analysis and well written. Very useful. Thanks.

    ReplyDelete

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