Advantage on damage rolls?

[Oramac]

Pretty much what the title says. Does anyone know what the math would be if one were to have "advantage" on damage rolls?

For example: Bob the Fighter hits BBEG with his longsword. He rolls 2d8 and takes the better roll, then adds his strength to the damage of the higher die roll (discarding the lower roll).

Thoughts? Good idea? Bad idea? Broken?

[Speely]

Savage Attacker is a feat that does this, effectively.

[Griswold]

The extra damage comes out to, on average, roughly a +1 bonus for 1d6 (https://anydice.com/program/a91), and a +3 bonus for a 1d12 weapon.

That said, advantage is a mechanism that is important if you have bounded accuracy on rolls which have binary outcomes as important design goals. The average benefit of advantage on a d20 is a +5, which makes you think it improves your chances by 25%. But, if you already needed a roll of 20, your chance of success only goes from 5% to about 10%, a much smaller benefit.

With damage, bounded accuracy doesn't matter as much, and except for killing blows, damage doesn't have a binary outcome. I don't know why you'd want to include it, rather than just giving flat bonuses.

[diabloblanco18]

With damage, bounded accuracy doesn't matter as much, and except for killing blows, damage doesn't have a binary outcome. I don't know why you'd want to include it, rather than just giving flat bonuses.

It's a neat dice trick, I suppose, like rerolling 1s and 2s with Great Weapon Fighting. Introducing that sort of variety among game mechanics might not do much to the underlying math, but it can make classes (or whatever options it's attached to) feel unique.

The OP hasn't said under what circumstances a character would be getting advantage on damage rolls, though, so I couldn't say whether it's a good, bad, or meh idea.

[Oramac]

Savage Attacker is a feat that does this, effectively.

Totally forgot about that!


The extra damage comes out to, on average, roughly a +1 bonus for 1d6 (https://anydice.com/program/a91), and a +3 bonus for a 1d12 weapon.

That said, advantage is a mechanism that is important if you have bounded accuracy on rolls which have binary outcomes as important design goals. The average benefit of advantage on a d20 is a +5, which makes you think it improves your chances by 25%. But, if you already needed a roll of 20, your chance of success only goes from 5% to about 10%, a much smaller benefit.

With damage, bounded accuracy doesn't matter as much, and except for killing blows, damage doesn't have a binary outcome. I don't know why you'd want to include it, rather than just giving flat bonuses.

Good to know. Thanks!


but it can make classes (or whatever options it's attached to) feel unique.

This, pretty much. The idea came up in my game last night, and I wasn't really sure how it would affect the mechanics.


The OP hasn't said under what circumstances a character would be getting advantage on damage rolls, though, so I couldn't say whether it's a good, bad, or meh idea.

The idea tossed around last night was for a Fighter archetype to get this as a class feature. Either always on, or some sort of X times per rest feature.

[Eric Diaz]

The extra damage comes out to, on average, roughly a +1 bonus for 1d6 (https://anydice.com/program/a91), and a +3 bonus for a 1d12 weapon.

That said, advantage is a mechanism that is important if you have bounded accuracy on rolls which have binary outcomes as important design goals. The average benefit of advantage on a d20 is a +5, which makes you think it improves your chances by 25%. But, if you already needed a roll of 20, your chance of success only goes from 5% to about 10%, a much smaller benefit.

With damage, bounded accuracy doesn't matter as much, and except for killing blows, damage doesn't have a binary outcome. I don't know why you'd want to include it, rather than just giving flat bonuses.

Well said! Savage attacker makes a little sense for barbarians, buy it's too much dice rolling for my tastes for too little effect. I think its actually around +2 for 1d12 instead of +3; the only circumstance where it makes a big difference is when the barbarian rolls a crit IMO.

[GlenSmash!]

Well said! Savage attacker makes a little sense for barbarians, buy it's too much dice rolling for my tastes for too little effect. I think its actually around +2 for 1d12 instead of +3; the only circumstance where it makes a big difference is when the barbarian rolls a crit IMO.

Even then I wouldn't take it over GWM. Those +10s can add up to way more damage than even a big boost to crits.

[Oramac]

So it looks like the TL;DR version is, it's not game breaking at all, and possibly not even that powerful relative to other options.

[Dirclaw]

There is a lot of misinformation about the benefits of advantage. An often quoted number for a d20 is +5, and while that's not wrong, it tells an incomplete story and is pretty simplified.

Advantage gets applied to rolls that only matter if you hit a certain amount, but that is not effected by how much you fail or succeed by. This means that its equivalent bonus is actually changes based on the difficulty of the roll. The idea that a d20 gives a flat bonus of +5 works if you need an 11 on the d20. With advantage, you only fail if you roll 2 dice 10 or less, which happens 25% of the time. (.5x.5). You have the same chance with a +5. You only fail if you roll a 5 or less.

If, instead, you needed to roll 19 on the dice, then you have a 19% chance of success with advantage (1-(.9x.9)), but would have a 35% chance of success with a +5. A better comparison at this stage would be a +2, which gives a 20% chance of success. You find similar differences at the low end as well.

+5 is given because it is fairly accurate for middle rolls, but it breaks down at extremes.

Damage, however is different, assuming that you aren't about to kill whatever it is you are fighting with this hit of course. Instead of affecting the chance to hit a certain number, we are instead dealing with how it affects the total average roll.

While there is a lot of computer simulations people like to run, its actually a really simple equation: The bonus of advantage is equal to ((x^2)-1)/6x, with x being the size of the die. This is really close to x/6, differing only by 1/(x^2), which gets smaller and smaller the lower the die is.

TLDR: The value of advantage is slightly less than the side of the die divided by 6.

[Griswold]

So it looks like the TL;DR version is, it's not game breaking at all, and possibly not even that powerful relative to other options.

Yeah, I think that about sums it up. Since it's not a huge buff, you could allow it to happen on every roll, but then that raises the question of is it more fun to roll more dice, or is rolling dice twice constantly going to be slow and annoying? If you want a unique mechanic around damage dice, you could give the fighter archetype the ability to just maximize the roll a certain number of times per short rest.

You could even base it off of the Sorcerer's metamagic, letting them choose between quickened attack (i.e. make a single attack for a bonus action), maximize damage, empower damage, heightened (which I guess would give you advantage on the attack roll), or distant (for ranged or thrown weapons, or heck, just to get reach on one attack sequence). It kind of comes off as a weird battlemaster, but you could fluff it plenty of other ways.