# House rule for calculating attack and damage in one roll

I played many different RP systems and prefer faster and more narrative games. I have a new group I DM and we play D&D, because I love the lore. For combat do I use theater of mind combat with abstract battle zones and this works perfectly and I play now with the thought of reducing the attack action to one roll and would highly appreciate your feedback about the implications of the house-rule.

## Motivation

1. Have one roll for attack and damage.
2. Better hits do more damage

### DM preparation

For Monster AC I add two more AC values. One with +2 and One with +9.

For PC weapons I calculate the min, average, max damage for each attack. This represents the quality of the hit and is connected to the three AC thresholds.

### During Combat

Player rolls attack and checks which of the three AC threshold he passes. You pass the AC and do min damage, you pass the +2 AC threshold you do average damage, you pass the +9 AC threshold, you do max damage.

### Math

In 5e the chance of hitting is on average 65%. Based on that a +2 mod on AC reduces the chance to 55%. And a +9 mod to AC reduces the chance to hit to 20%.

The three brackets represent you have a 65% chance to do minimum damage, 55% to do average damage and 20% to do max damage.

If you calculate the average distribution for this simplified damage distribution ä, you end up at the same average as rolling the damage dice. The three brackets for damage are a reduced damage distribution of the damage roll.

The difference is, a better it is directly higher damage. A stronger character has then a higher chance to do max damage on a weaker monster.

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– Jack
Mar 29 at 10:48
• You can do something similar by rolling both dice at the same time without all of the mental gymnastics. Know your weapon damage dice and roll that along with the d20; on a miss the dice are ignored. Request for clarification: did you construct a table for your players to consult or is all of this done with mental calculations? Lastly: don't use code block, use actual quotes or parens. Code blocks mess up screen readers. Mar 29 at 11:58
• Despite my effort, I wasn't able to imagine how it works. Maybe some tables and example of actual use in play would make it easier to understand? As for the last sentence, please avoid open ended "What do you think about this?" and similar. Questions where every answer is equally valid are forbidden, see help center. Ask a question in a way that would allow objective vote up or down on answers, not based purely in voters opinion, but on the answer merit and how good it answers the question asked. Mar 29 at 13:39
• It seems like this level of complicated, system-altering, homebrew for such a fundamental part of the game prompts the question "why not play a different system you're more happy with, and use D&D lore and flavour?" (I'm not sure if that's appropriate as an answer, but happy to post it as one if so) Apr 4 at 7:51
• @DaniO'Shea that is actually a very good frame challenge. I'd definitely see that as an answer. Apr 4 at 7:59

## Frame challenge: keep the lore and flavour, but use a different system.

I have to confess that I don't fully understand your proposed house-rules, but like the other answers here, I don't believe they will lead to combat being sped up.

You say that you are more familiar with - and prefer! - more narrative and fast-paced systems, but enjoy the lore of D&D. That being the case, why not take the aesthetics and flavour of whatever D&D setting you enjoy, and map that onto the mechanics of a system you prefer?

Especially if your players are also new to D&D, having to learn a new system as well as the far-reaching mechanical changes introduced by your house-rules seems like a bit of a potential nightmare from their point of view.

I played in a homebrew game once that went through several different systems (RISUS, GURPs, a "D20 Modern" homebrew system) before we settled on one we liked for the game, but the setting/lore/story of the game (time travellers trying to stop a Terminator-like dystopian future) stayed consistent throughout. I see no reason for your setting having to change.

• Yeah I see the same problem with them learning two things at the same time. Had just fun calculating probabilities:) Apr 4 at 8:15
• It might be worth having a Session Zero and working out what kind of game/maths/playstyle your players like, so you can work out what will be the most fun going forward. Also, I appreciate the accept, but you might want to hold off on accepting an answer till some more come in - the question is only a few days old, and there are some higher-voted answers. Apr 4 at 8:17

### It does not seem that this process will speed up the fights.

The actual rules consist in

• making an attack roll: roll a d20 + mods
• check if the result is greater than the target's AC
• in this case, roll the damage and subtract the damage to target's HPs

This could be sped up a little bit by rolling both the d20 and damage die/dice, considering the latter only if the attacks is successful.

The proposed method consists in

• rolling an attack roll: roll a d20 to mods
• compare with 3 different values and check which success degree has been achieved
• subtract the relative damage, looking at the (small) damage table.

It actually seems a little bit more lengthy, since one has to check which degree of defense (AC, AC+2, AC+9) has been overcome.

### Other issues

As written, it is not clear why these 3 particular values had been chosen, and there is a huge gap between the second and the third AC's degrees. Moreover, it lacks of critical hits.

### There are other ways to speed up the attack and damage rollings

At my table, in case there is only one attack, we roll at the same time the d20 and the damage dice, and consider the latter if and only if the attack lands.

In case a player (or a monster) has multiple attacks, we roll all the attack rolls and check which attacks are successful, we then roll the damage dice. If you want to roll also the damage dice together with the d20s, you may use dice of different colors and associate each d20 and each damage die to one attack.

• Thank you for you answer! In a way I replaced the math of adding dice south a threshold comparison. The three thresholds are build based on the average hit chance of a character against AC of 65%. This would be minimal damage. The +2 has a 55% chance and represents average damage. The +9 means only 20% of all rolls hit this threshold and do max damage. If you average the damage over the distribution it is roughly the average damage of the attack dice. Apr 4 at 7:34

Your house rule would change how damage works and how the game plays fundamentally.

Hitting a thing and doing damage are two seperate rolls for a reason. So it can be balanced that something that hits often and does a little damage and something that hits rarely and does a lot damage are roughly equal. You are removing this balance.

Take a band of kobolds. Iconic beginner opponents, that are only dangerous because when they gang up, they hit easier. Still do measly damage though. With your change, they will not only hit more often, they will also do more damage because their hits will be "better". A group of kobolds will wipe the floor with the party after your change.

Take a giant. Also pretty iconic, not that agile, but when they land a blow, boy, ouchie. But no longer with your changes. The fact that they hit rarely means they now also don't do any significant damage anymore, since all their hits are "barely" connecting.

On the other hand side, we have the players:

The nimble athletic but fragile elf can take enourmous amounts of punishment now. Not only is he hit less often (same as before), but since the hits that do land are not as "good", the damage is minimal each time. They don't need constitution as a stat, they have completely replaced it with dexterity, even the weak points.

Or the slow, cumbersome, but muscular tough dwarf. They are hit often, but in former times they could shrug it off with extra hitpoints from their constitution. No longer. Every hit will hit them hard. Way harder then the elf. Their extra hitpoints will be gone in no time and they will wish they had played an agile but fragile dwarfen dancer instead of the smith with a two handed hammer. At least then they could have taken on the orcs in direct combat, outdanced and outdamaged them.

So your changes will seriously impact the balance of the game, moving it from the current balance to basically CON be a dump stat and DEX being the must have for all classes no matter what.

Kobolds will be the bane of high level adventurering parties, while giants will be fended of by the halflings pet companion. Elves will be the sturdy tanks, while dwarves will hide behind them.

For me, elves being nimble, dwarves being sturdy, giants being dangerous, kobolds being a nuisance, that is part of the lore. If that isn't the case any more mechanically, the lore will collapse, too.

There seems to be a misunderstanding of what a d20 roll means.

A d20 roll doesn't measure the quality of the check. Instead, it provides a single binary value (either you pass, or you fail) that is then further refined by the rules of whatever check you're doing.

If the target CD is 10, it doesn't matter if you got it done with 19 or 11. Both of those are equal successes.In the same vein, it doesn't matter if you fail with a 2 or a 9 - both of those are still fails.

The exceptions for those are crits, but those are still bound to the idea that the "grade" of the attack is determined by the numbers that show up on the damage dice, not the attack itself. Of course, having more dice to roll often means higher damage, but there isn't a guarantee there.

The sort of grading you're after is difficult to implement with a jumpy dice like the d20. If you want to go for a rule like this, you'll need to do a deeper - and more complex - change on the combat system, that may or may not play well with the rest of the game.

I would strongly advise against such a house rule.

• Thank you for you answer! I see the issues you point out. I’m my head was the AC just a threshold tuned to a average hit chance of 65% and a +8 on a roll another threshold with a 25% chance of happening. And instead of rolling the damage dice have the distribution reduced to three values. Apr 4 at 7:30

Off top of my head, there are a few corner cases where this house rule needs to be perfected, such as when damage rolls are supposed to be re-rolled. For example, the Flames of Phlegethos feat (from Xanathar's):

When you roll fire damage for a spell you cast, you can reroll any roll of 1 on the fire damage dice, but you must use the new roll, even if it is another 1.

BTW:

Other considerations aside, as far as I can see, this house rule can be fun, so if your group is happy with this house rule, I don't see why not using it.

On the other hand, from my experience, I would be tempted to say that there can also be an emotional factor involved: for some players the fun also come from rolling the dice, and the more dice rolled, the bigger the satisfaction.

(disclaimer: I know that I should avoid adding considerations based on opinion and/or personal experience, but the question was explicitly asking for feedback about implications and this is a real implication, despite it cannot be found in the rulebooks)

• Opinions based on personal experience are exactly the sorts of opinions we want here. It’s wild guesses based on no experience that we prefer to avoid. Apr 4 at 11:20