5E: Advantage / Disadvantage and how you are applying it....

[Fake Healer]

So my group is playing 5E and we are enjoying it very much. I am not seeing us using the Advantage/Disadvantage system much though and I want to figure out why.
The actual rules surrounding when they should be used seems to be mostly "when the DM determines you have one". It doesn't clearly define when to use them though.
Here are some questions:
*Is it basically a replacement mechanic for +2/-2 adjustments?
*If you are a rogue using your sneak attack do you get advantage?
*Does higher ground/lower ground trigger use of Adv/Disadv?
*How about surprise round? Does everyone participate in combat on the surprise round with the surpriser getting advantage on attacks and the surprised getting disadvantage?
*How would this work with skills?

I really like the rule but it is so vague on when to use it that it almost doesn't seem to exist in my game currently and that is really a shame. I want to rectify this.

[DungeonMastering.com]

Fake Healer wrote:

*If you are a rogue using your sneak attack do you get advantage?

I believe you HAVE to have Advantage to get the extra Sneak Attack Damage: "Once per turn, you can deal an extra 1d6 damage to one creature you hit with an attack if you have advantage on the attack roll."

[DungeonMastering.com]

Fake Healer wrote:

*Does higher ground/lower ground trigger use of Adv/Disadv?

I believe so. Essentially it's up to the DM/Common Sense, but here's a compiled list:http://www.reddit.com/r/DnD/comments/29xk0j/5e_summary_of_situations_causin g_advantage_or/

[Fake Healer]

Thanks for the list, it should help. Also I am seeing the Assassin archetype for rogues has an ability that gives him an advantage when he has surprise on a foe(like in the surprise round) so I am guessing that normally surprising someone in the surprise round doesn't give advantage to the attacker otherwise that ability wouldn't be very special.
A rogue can also get sneak attacks off without advantage if an ally is within 5' of the target apparently but it isn't an advantage situation....makes getting the sneak damage easier but without an advantage. Interesting....
I wonder what the average of 2d20 drop the lowest is but I don't know the formula to figure it out....I wouldn't mind knowing what the average bonus/penalty would be from Advantage/Disadvantage.

[DungeonMastering.com]

De nada. Luckily, someone already did the heavy math for us: http://andrewgelman.com/2014/07/12/dnd-5e-advantage-disadvantage-probabilit y/

[Southeast Jerome]

Fake Healer wrote:

So my group is playing 5E and we are enjoying it very much. I am not seeing us using the Advantage/Disadvantage system much though and I want to figure out why.

The actual rules surrounding when they should be used seems to be mostly "when the DM determines you have one". It doesn't clearly define when to use them though.
Here are some questions:
*Is it basically a replacement mechanic for +2/-2 adjustments?
*If you are a rogue using your sneak attack do you get advantage?
*Does higher ground/lower ground trigger use of Adv/Disadv?
*How about surprise round? Does everyone participate in combat on the surprise round with the surpriser getting advantage on attacks and the surprised getting disadvantage?
*How would this work with skills?

I really like the rule but it is so vague on when to use it that it almost doesn't seem to exist in my game currently and that is really a shame. I want to rectify this.

I would get creative and ask your DM whether different things can give you advantage as they come up. The rules are left intentionally vague to encourage creativity by the players and the DM, but if your DM is in the 3.5/Pathfinder mindset, it's easy to fall into the habit of searching for the specific rule that covers this specific situation. Once your DM starts making rulings, I think you'll see him looking for ways to apply it creatively too.

*Is it basically a replacement mechanic for +2/-2 adjustments?
Mostly, yes. The math gives you an effective bonus of between +1 (to roll a 2 or 20) and +5 (to roll a 10-12), depending on the number you need to hit. Average bonus is +3.5 for advantage, and -3.5 for disadvantage.

*If you are a rogue using your sneak attack do you get advantage?
Reverse that - if you have advantage, your attack deals sneak damage. You can also get sneak damage if you hit an opponent who is within 5' of an ally (i.e., in melee) - no advantage on the attack roll, but you deal sneak damage if you hit.

*Does higher ground/lower ground trigger use of Adv/Disadv?
No specific rule that I'm aware of, but many DMs would make that ruling, or take it case by case. Another example is flanking - there are no flank rules in the PHB, but a DM may rule that a flank gives you advantage. The DMG may have more optional rules for Advantage/Disadvantage, but at least in the PHB, I think the lack of too many specific rules is intentional.

*How about surprise round? Does everyone participate in combat on the surprise round with the surpriser getting advantage on attacks and the surprised getting disadvantage?
Again, no set rule that I know of. On the one hand, it makes mechanical sense, but it does step on the toes of the Assassin Rogue a bit, since he gets advantage against anyone who hasn't acted in combat yet. Limiting advantage to opponents who are actually surprised and only during the surprise round would probably be a decent compromise since the Assassin also gets it against anyone who's flatfooted, surprised or not.

*How would this work with skills?
I feel like disadvantage comes up more often than advantage for skill checks. Like picking a lock in the dark, or trying to bluff while your drunk. The Help action can be useful here - instead of making his own knowledge roll, a low Int character can "help" a high Int character and give him advantage with the higher Int bonus for both rolls.

[Hudax]

Fake Healer wrote:

The actual rules surrounding when they should be used seems to be mostly "when the DM determines you have one". It doesn't clearly define when to use them though.

Any time you roll a d20 you have an opportunity to roleplay to gain advantage. The rule makes the whole game reward roleplaying.

Instead of spending their time searching through the books looking for bonuses, players will be spending their time imagining what they can do tactically/in-character to gain advantage. You're in the game instead of in the rules.

It's just simply a brilliant mechanic and if you're leaving it out, 5e is going to be just another ruleset. If you make the small effort to use it thought, the game comes alive.

[Terquem]

DungeonMastering.com wrote:

De nada. Luckily, someone already did the heavy math for us: http://andrewgelman.com/2014/07/12/dnd-5e-advantage-disadvantage-probabilit y/

I looked at that and maybe I didn't look close enough, but did it include the process by which those numbers were calculated. that's what I'd like to learn more about.

[Southeast Jerome]

Terquem wrote:

DungeonMastering.com wrote:

De nada. Luckily, someone already did the heavy math for us: http://andrewgelman.com/2014/07/12/dnd-5e-advantage-disadvantage-probabilit y/

I looked at that and maybe I didn't look close enough, but did it include the process by which those numbers were calculated. that's what I'd like to learn more about.

TL;DR:

PA=1-(1-(21-x)/20)^2
x is the target number on a d20 roll
PA is the probability of meeting that number on at least one of two d20 rolls

PD=((21-x)/20)^2
PD is the probability of meeting that number on two consecutive d20 rolls

Longer version:

1) calculate probability of hitting a target number - for d20 it's easy, 5% for every number under 20.

PN=(21-x)/20
x is your target number (on the die, not necessarily the DC)
PN is the probability of hitting or exceeding X on one d20 roll

2) Disadvantage is easier to calculate. Since you have to take the lower number, it means you have to meet or exceed X on both rolls.

PD=PN^2=((21-x)/20)^2
PD is the probability of succeeding on two consecutive d20 rolls

3) Advantage is trickier, but still straightforward. Since you have to only make your number on one of two rolls, the other way to look at it is to figure out what the probability of failing an advantage roll for a given number is.

PNf=1-PN
PNf is the probability of failing on a d20 roll

PAf=PNf^2=(1-PN)^2=(1-(21-x)/20)^2
PAf is the probability of failing two consecutive d20 rolls

PA=1-PAf=1-(1-(21-x)/20)^2
PA is the probability of succeeding on at least one of two d20 rolls

(And now we've reached the limits of what I remember from college statistics) :)

For more dice, just change the exponent to the number of dice you're using. "^3", "^4" and so on. Each extra die gives you diminishing returns, but the jump from 2 to 3 dice is still significant. If I were houseruling it, I'd probably allow for stacking up to 2 advantage dice (3 dice total) to see how it works, but that's probably the limit before the complexity overtakes the benefit. I have an excel sheet that I've been playing around with - I'll post on google when I get a chance.

[Arma virumque]

Southeast Jerome wrote:

Fake Healer wrote:

*How about surprise round? Does everyone participate in combat on the surprise round with the surpriser getting advantage on attacks and the surprised getting disadvantage?

Again, no set rule that I know of. On the one hand, it makes mechanical sense, but it does step on the toes of the Assassin Rogue a bit, since he gets advantage against anyone who hasn't acted in combat yet. Limiting advantage to opponents who are actually surprised and only during the surprise round would probably be a decent compromise since the Assassin also gets it against anyone who's flatfooted, surprised or not.

Another rule to keep in mind is that hidden attackers gain advantage. So for example, I would rule that in a surprise round, ranged attacks get advantage against surprised opponents, because it's reasonable to interpret that being surprised = didn't see the person aiming the ranged weapon.

For the same reason, I might rule that melee attacks sometimes get advantage in a surprise round, but only in a close quarters situation where the attacker can reasonably "step up and swing" without being seen first. But if the attacker has to cover significant distance before attacking, I would rule that he's not hidden and therefore not eligible for advantage.

[Giorgo]

As a GM I like the freedom to add advantages and disadvantages, almost all of which I apply "on the fly" as the situation suggests and if it makes the story move along/raise intensity.

The Elven Fighter-Archer climbs to the top of the wagon to get height benefit over the goblin ambushers below? Sure why not, here is an advantage, enjoy.

The PCs roll hot dice and kills the bugbears elite wolf pet, downs the bugbear chief with a critical hit with a javelin AND with a greatsword in the same round? Get a free advantage as the surviving minions automatically fail a morale check and turn their backs as they get the hell out of there. They just saw their boss get owned like a newb, they just want to flee before the murderhobos can get another chance to kill them...

The PCs find a way to use their background in a creative way to their benefit and role play well? Here is a free advantage on your next diplomacy check. Make it count.

And so on. My players are starting to get creative on thinking of ways to get more advantages coming their way. (Grin)