Designing a d20 RNG

[Username17]

So does this work for a fixed HP system?

HP = 10
Attack = 2d10 + Mods
Defense = 11 + Mods
Damage = 2d10 + Mods
Toughness = 7 + Mods
Beating toughness by 1+ gives 1 damage, 5+ gives 3, 9+ gives 6, and 13+ gives 10 damage.

That would either work or not work depending on your design goals and the available mods. In such a system you would one-shot an opponent with equal mods 0.55% of the time, which isn't much. You'd do no damage at all 56.55% of the time, which is kind of a lot. An average hit does (.34x1+.30x3+.14x6+.01x10) = 2.18, which hits 55% of the time. An equal mods combat takes an average of 9 attacks, although it has a 1.6% chance of ending in two attacks or less (for each player).

Adding +1 to-hit increases chances of hitting by 9%, adding +1 damage raises average damage per hit to 2.58, which means that +1 to-hit is a 16% increase in damage per round, and +1 damage is an 18% increase in damage per round. Further increases are diminishing for attack bonuses and accelerating for damage bonuses (the second +1 to-hit increases absolute to-hit by 8% and the second +1 to damage adds .68 damage per hit).

Whether those are numbers you want depends on how the system works and how long you're trying to get combats to last and how much failure you're willing to accept. And of course, you need terminology that distinguishes the damage roll from the damage output if they aren't the same thing. Like, it doesn't matter if you roll d8+6 damage and then inflict 11 damage when you roll a 5 in D&D because the numbers are the same. But if you're going to use a static hit point transform it's totally not OK to roll 2d10 + 3 damage and then inflict 3 damage because you rolled a 9. Because those numbers aren't the same, they need different names. Like "Attack Strength" for the bonus to the damage roll and "Damage" for the actual number of hit points lost or whatever.

-Username17

[DenizenKane]

Hm, alright. Didn't think that one through enough.

Probably works better more linear.

HP = 10
Accuracy = 2d10 + 9 Str + 2 Focus + 2 Flanking + 1 Level = 13
Defense = 10 + 9 Dex + 2 Light Armor + 1 Level = 21
Damage = 2d10 + 9 Str + 6 Greatsword + 2 Focus + 1 Level = 18
Toughness = 10 + 6 Str + 2 Light Armor + 1 Level = 19

Damage Dealt = Damage - Toughness

72% Chance to Hit, AVG 10 Damage (2d10-1), AVG 7 DMG per round, kills in 1-2 rounds.

2 more levels above on defender drops hit chance to 55%, and AVG DMG down to 2.5, which would take the attacker 4 rounds to kill.

Is this worth doing over the HP per level system that 3e uses?

Also, yeah I'm going to be using stats. The 4: Str, Agi, Int, Pre.

EDIT: The more I look at this, the more I love it, so elegant, needs tuning and a game built around it, but honestly its nice. Also, you can decouple armor and level from your to-hit to get a "realistic" effect on hit chances, while scaling damage with level so higher level stuff shrugs off attacks even if they molest you. Heavier armor could have give you a dex penalty, but a soak bonus.

[deaddmwalking]

I don't think you have a clear explanation of your Damage and your Toughness.

Adding two-digit numbers isn't super hard, but subtracting them isn't usually something to do at the table. If you choose NOT to simplify it, you should explain why. Is Toughness supposed to scale so that dragons are safe from low-level enemies? Do hit points always stay at 10?

Keep in mind that there are going to be (average) 4 PCs, each of them making an attack. If they're tightly clustered as far as abilities, that'll average 1-2 hits which wouldn't always be 1-2 rounds.

[DrPraetor]

Again, this depends on your design goals, but 2D10 for damage against 10hp seems awfully swingy.

Specifically, an attack that *averages* 1hp of damage (on an 11) will take you down in one hit 1% of the time (on a 20).

It's most swingy for attacks that do on average 5hp of damage, which will take the target down in one hit on 16+ (15% of the time) and do nothing on a 6- (also 15%).

If you want to roll 2D10 for damage without doing math on it - which seems like a laudable goal - maybe give people 20hp instead of 10?

[DenizenKane]

Yeah, the numbers are all in need of tweaking, I was thinking it probably needs 20hp.

And, yeah the point is that HP is constant, and the numbers should work if I tweak them properly. A CR10 Dragon still has 20hp, but his toughness is probably in the 30s or so.

[Mord]

That's where things like Abilities and Character Classes come in. By describing a character as "smart" or "a techie" or whatever you can get some information across to the other players that is packaged in a manner the other players can digest and interpret and most importantly extrapolate from.

An additional tool you might leverage to accomplish this is skill groupings - you can still avoid having an INT score on your sheet if you have your "smart" skills grouped together in such a way where players can still get meaning from someone saying "I specialize in tech stuff".

You could even include a rule where unexpected scenarios that don't fit nicely with any individual skill still allow you to default to your lowest skill within the group that best corresponds to your problem-solving approach, which basically becomes a backdoor way of having the "all purpose" modifier that you would otherwise lose by not having a defined INT bonus no more. If you want to get really elaborate, allow the player to spend narrative currency (or do some good RP) to instead use a specific (better) skill within the group.

If you're going to have Warriors, it's potentially a nice thing to be able to differentiate between different kinds. Especially if it would be plausible that more than one player would be playing one at the same time. And thus having some kind of additional qualifier you can put on "Warriors" is a good thing. Stats and themes and kits and shit are good for that.

An additional tool for this: subclasses. If you make "fast guy", "tanky guy", and "smashy guy" defined subclasses of "Warrior", you can differentiate two characters of the same archetype in a way that is probably more effective than intuiting a role description from the character's total set of stat numbers and feat/fiddly knob selections.

[deaddmwalking]

Yeah, the numbers are all in need of tweaking, I was thinking it probably needs 20hp.

And, yeah the point is that HP is constant, and the numbers should work if I tweak them properly. A CR10 Dragon still has 20hp, but his toughness is probably in the 30s or so.

The first thing you want to avoid is rolling a 'successful attack' and then finding out that you didn't roll any damage at all. You're basically just wasting time.

Just spitballing, but let's say someone has an Agility of 10 and a Toughness of 10. Let's add those together and we make their 'Defense' 20.

You roll an attack roll of 2d10+STR (10). If you 'hit' 20, you do 1 point of damage. If you hit 25, you do 2 points of damage. If you hit 30 (limit of possibility), you do 3 points of damage (ie, every 5 points you beat the Defense, you deal +1 damage.

If the opponent stays the same, but I'm 5 levels higher, I'd be rolling 2d10+STR(10)+LVL(5) for a range of 16-35.

If I roll a 4+, I'll do at least 1 point of damage (97%). If I roll a 9+ (72%), I'll deal 2 damage; if I roll a 14+ (28%), I'll deal 3 damage. If I roll a 19-20 (3%) I'll deal 4 damage.

Removing a roll reduces complexity. Scaling damage with the attack roll makes intuitive sense - better attacks deal better damage.

[DenizenKane]

1 roll is not enough for an attack, that's too simple, and dividing by 5 doesn't make it any easier or better. In nWoD they use 1 attack roll, and it sucks. correct me if I'm wrong, but dividing by 5 has about the same effect as multiplying the HP by 5, but the math now has division.

Well apparently the worst excesses of the combat system were best summed up by the idea that immortal vampires with super speed could take on a second grade special ed class in a stick fight and take out more than two of the vicious children before they were brought down. I don't think this can be said enough times: there is no fucking damage roll. No damage, no soak. Your to-hit roll is also your damage roll. And it's a dicepool system. If I roll 2 dice I am handing out exactly and linearly half as much damage as a guy rolling 4 dice. If there are two of me, we are handing out the same damage (actually more, because there are multiple attacker bonuses, but you get the idea). This means that a handful of anyone with sticks has the combined offensive output of anything in the whole game. So actual combat is pretty much just War with the cards replaced by piles of dice. My side has a pile of dice, so does your side. The biggest pile almost invariably wins and no one cares.

Okay, another example.

Two Characters

"Warrior" Level 1
Str 18
Agi 16
Int 12
Pre 10

Armor: Plate (+6 Toughness, +6 Energy Resist. -4 Dex, +2 AC), Weapon Greatsword (+2 Attack, +6 Damage)

"Mage" Level 1
Str 12
Agi 10
Int 18
Pre 16

Armor: Mage Armor (+2 Toughness, +2 Energy Resist), Weapon Firebolt (Int +2 attack, +4 damage, fire damage, ranged touch 60ft range.)

Warrior Attacks Mage
Attack = 2d10 + 9 Str
Defense = 10 + 5 Agi = 15
85% chance to hit.
Damage = 2d10 + 9 Str + 6 Greatsword = 15
Toughness 10 + 6 Str + 2 Mage Armor = 18

He'll be swinging for an average 8 damage, x.85 = 6.8
At 10 hp, that would be 2.
At 20 hp, that would be 3.

Mage hits the Warrior with his firebolt.

Attack = 2d10 + 9 Int + 2 Firebolt = 11
Defense = 10 + 6 Dex = 16
Damage = 2d10 + 9 Int + 2 Firebolt (Fire) = 11
Defense = 10 + 9 Str + 6 Energy Resist = 15

Mage is gonna connect fireball 90% of the time, and his damage will be an average of 7 a round, 7 x.9 = 6.3
10 HP = 2 Hits
20 HP = 3-4 Hits.

20hp is probably better, and I like that is matches MtG's health total because I intend on using a 6 color alignment wheel. (Red, Orange, Yellow, Green, Blue, Purple)

[Foxwarrior]

The Frank Trollman argument you provide in opposition to one roll attacks is pretty specific to the way that system works. If you look at, say, D&D saving throws, there's also only one roll per kill spell, but five DC 10 saves is not the same as one DC 50 save.

That's not to say I'm necessarily opposed to having more than attack strength vs defense for an attack; there are advantages to being able to differentiate types of attacks and characters by just adjusting numbers instead of drowning in unique tags. But... I'm not yet convinced that one roll is too simple for an attack.

[deaddmwalking]

There's a certain danger to 'ivory tower' design. Now, if you don't know what your goals are, you're not going to know if you've achieved them. You've certainly put the cart before the horse. But let's take some actual rolls:

Warrior versus Mage (3 rounds): 2d10+9 25 2d10+15 31 2d10+9 18 2d10+15 28 2d10+9 24 2d10+15 34...

I did one set of rolls for 3 rounds of combat. I rolled the Warrior's turns first, followed by the Wizard, and we're smart enough to sort them out.

Round 1
Warrior Attacks Defense 15 and rolls 25. Damage rolled is 31. Soak is 18. Total damage is 13. With 10 hit points, the fight is over. Let's assume 20 so we can continue.

Wizard attacks Defense 16 and and rolls a 21. Wizard rolls 26 damage. I don't know why the Warrior has Energy Resistance, but you say he does, so we subtract 15. The wizard deals 11 points of damage to the warrior. Again, if we had only 10 hit points, this fight would be over. Apparently, determining initiative is REALLY important - this would be Rocket Tag...

Round 2
The warrior rolls an 18 for attack, which hits. He rolls 28 for damage. We subtract 18. The wizard falls, even with 20 hit points. It turns out that while on average it might take 3 turns, even with the compression toward the mean that 2d10 provides over a d20, it doesn't always work out to be average. But let's assume the wizard is alive (maybe he won initiative?!).

The wizard rolls a 22 to hit which is enough to hit. He rolls a 23 for damage. We subtract 15. That results in 8 total damage. That's only 19 damage, so the Warrior is still up with 1 hit point (that is, if he didn't go first).

Round 3
Even though the wizard is dead, I rolled three rounds of combat dice. Warrior rolls 24 for the attack and 34 for damage (exceptionally good roll). Mage armor is better than real armor I think, because the Wizard has 18 soak, but that's still 16 damage getting through. The wizard doesn't have to worry about being dropped in a single hit but just barely[/b].

If the wizard weren't already paste, he rolls a 26 for attack and a 29 for damage. That's really good - 14 damage. If he had rolled this in Round 2, he would have won (provided he won initiative).

Now, let's compare to the 'too simple' recommendation.

Round 1
Warrior rolls 25 versus 15. Hitting 15 is a hit, +10 is two additional hits for a total of 3 hits.

Wizard rolls a 21 versus 16, that's two hits.

Round 2
Warrior rolls 18 versus 15, resulting in 1 hit (total of 4).

Wizard rolls 22 versus 16, that's two more hits (total of 4).

Round 3
Warrior rolls 24 versus 15, that's two hits (total of 6).

Wizard rolls 26 versus 16, that's 3 hits (total of 7).

And that's 3 rounds. Of course, that's just slugging it out. From running this one as proposed, there was really no reason to do anything tactically - every attack hit, so looking for additional bonuses to hit weren't necessary. Damage rolls happened to be high - they could have been low instead and 3 hits in a row might not have done ANY damage.

If you determined damage from the attack roll, you'd suddenly have a lot of reason to think about increasing your roll. If tripping someone gave you a +4 to attack (or -4 to opponent's defense), the warrior would have added 1 hit in round 2 and 1 more in round 3. There could be a lot of focus on finding attack bonuses (which would translate directly into damage bonuses) so the 'simple system' might actually invite more complexity in terms of tactical play.

[DenizenKane]

Couldn't the system work the same with just an single attack roll vs a number that combined AC and damage resistance

No. Under such a system death would always be way too common - like when you cast Save or Dies in D&D now. Also, you couldn't represent fights against mosquitoes well at all - since there would be no way to be very dodgy yet extremely fragile (which is what you want when dealing with Stirges and the like).

You either hit or don't, then you see how much damage you do - these have to be separate rolls because some enemies are supposed to be hit a bunch of times before they go down, and some enemies are supposed to go down in one punch.

Frank, again, on a system just like the one I'm proposing, from 2004.

I personally don't see why you'd want 1 attack roll. It only takes another 20-30 seconds to roll and compare another dice. and I consider a feature to be easier to land hits in some situations, but harder to do damage. The whole system is designed to keep attacks against relative levels the same instead of having your HP scale into the 200-300+ range by level 10, and having to add together handfuls of d6s for damage.

And, even with the method where you get bonuses to damage for your attack roll, could be added damage to your damage roll. You could make every 2 you beat the defense by add 1 to the damage roll or something like that.

Also, Alternately, you could allow the Target to roll soak instead of you rolling damage, but its statistically the same. (If your damage and soak were both to roll 1 time for a whole AoE.)

And if the survivability isnt working out quite right, its because the numbers aren't right and it needs to be tweaked.

[deaddmwalking]

Frank, again, on a system just like the one I'm proposing, from 2004.

I'll let Frank speak for himself, but I don't think your system is 'just like' the one you're proposing. Remember, you said that everyone has 20 hit points. A mosquito in your system could be represented by Low Defense/No Soak.

I personally don't see why you'd want 1 attack roll.

I don't. I use an attack and damage roll in my system. But my damage rolls actually mean something. Originally you proposed:

Beating toughness by 1+ gives 1 damage, 5+ gives 3, 9+ gives 6, and 13+ gives 10 damage.

That's a lookup table that nobody is going to internalize. Why can't you get 2, 4 or 5 damage? I didn't see you specifically repudiate this idea, but you should, because it is really bad.

It only takes another 20-30 seconds to roll and compare another dice. and I consider a feature to be easier to land hits in some situations, but harder to do damage. The whole system is designed to keep attacks against relative levels the same instead of having your HP scale into the 200-300+ range by level 10, and having to add together handfuls of d6s for damage.

Doing 34-18 isn't super-fast for most people at the table. If your level is ~20 (assuming you haven't dropped the +1 Attack/Damage/Defense/Toughness for levels), you'd be subtracting 54-38. Now, if you know your opponent is the same level as you, you could 'straight roll' without adding the level bonuses, but if the levels are different you're going to have to add some portion of your bonus. If your're 3 levels higher than your opponent you're at 37-18 which means you get to carry a tens in your mind. Joy.

And, even with the method where you get bonuses to damage for your attack roll, could be added damage to your damage roll. You could make every 2 you beat the defense by add 1 to the attack roll or something like that.

More math! Yay!

Also, Alternately, you could allow the Target to roll soak instead of you rolling damage, but its statistically the same. (If your damage and soak were both to roll 1 time for a whole AoE.)

Yes, you could do this. In fact, you could do anything. Your system is limited only by your imagination. But your imagination is ignoring the practical effects of your choices. When Damage is 2d10+18-19, it's probably FUNCTIONALLY 2d10 most of the time. The extra operations aren't contributing the the game. They're adding apparent complexity and making the math more difficult, but they're not changing the results in a meaningful way. Adding a constant to a die roll then subtracting a similar but needlessly DIFFERENT constant doesn't change the consequences enough to justify the extra steps. You're turning in a circle just to end up where you started before you did anything.

[DenizenKane]

Yeah, I dropped the damage conversion thing and it's just straight damage now. Guess I wasn't specific enough??

You roll 2d10 to hit vs defense, and 2d10 for damage vs soak, and you subtract soak from the damage dealt. Done. Easy peasy. Only thing that needs fleshing out it the numbers and base DCs and all that.

And, a dire mosquito is represented by high defense because he's hard to smack, and low soak because he splats in a hit.

[deaddmwalking]

Your numbers only make sense after you answer basic questions.

For example, is it possible for a mosquito to survive being hit? Should it be?

If I have a +15 damage and it has zero soak, it is possible I do less than 20 damage. Are you okay with that?

[DenizenKane]

Yeah, if we're talking an actual mosquito, it could easily have -20 negative soak or something, I mean I can squish it with my finger if I'm 90 with diabetes?

[Username17]

I don't think it is remotely acceptable to have a combat centered game where there is a single roll for attacks. An attack roll plus a damage roll is a basic minimum and not having that has never worked out and will never work out. It just obviously won't.

That being said, before anyone can make sense of whether your numbers make sense, it's important to know what your goals are. When discussing damage scaling, it is absolutely vital to know when and to what degree powerful attacks are supposed to clear out weak targets. Presumably you have giants that are supposed to smash basic orc soldiers in one hit, but exactly where that kicks in is an absolutely core design goal that has to be explicitly defined before any numbers anywhere can be evaluated as to whether they meet those goals.

Consider the giant with its head in the clouds. It's basically a terrain feature and presumably if it stomps on a basic soldier that soldier should die. But also consider Andre the Giant - he's basically a big guy. And while you might want him to be able to one-punch enemies some of the time, it's not going to be weird if some enemy soldier has to be hit twice. Obviously there's a really big range between those, and traditional D&D Giants don't really get that much bigger than Andre until 11th level (Fire Giants are less than 3 meters tall, and could plausibly fit inside most houses).

-Username17

[deaddmwalking]

Yeah, if we're talking an actual mosquito, it could easily have -20 negative soak or something, I mean I can squish it with my finger if I'm 90 with diabetes?

So you'd give something negative soak before reducing the hit points?

I mean, giving a mosquito 1 hit point and zero soak is functionally the same as giving it 20 hit points and -20 soak, but you're adding complexity for essentially no benefit.

Why is having every creature have 20 hit points a benefit a priori of anything else?

[Username17]

So you'd give something negative soak before reducing the hit points?

I mean, giving a mosquito 1 hit point and zero soak is functionally the same as giving it 20 hit points and -20 soak, but you're adding complexity for essentially no benefit.

Why is having every creature have 20 hit points a benefit a priori of anything else?

That's easy: Scalability. A fixed hit point system scales infinitely in both directions by definition. A variable hit point system does not. The moment you add or subtract hit points, the game stops scaling. If you deem that Mosquitoes have 1 hit point rather than a penalty to their soak roll, your system is not capable of handling mosquito fights using the standard resolution mechanics. That probably doesn't matter, but if it for whatever reason comes up (such as mind controlling tiny animals to use as messengers or spies or something), then your game system hits a breaking point.

As long as you keep to fixed hit points, your system can model rat fights or world turtles fighting with the same relative outputs as it handles goblins stabbing each other. If you vary the hit points, there are hard limits up and down before the game stops making any sense. And in the context of open world RPGs, those limits come up surprisingly frequently. SR4 chokes on its own dick when you shoot at vehicles of any kind. Dungeons & Dragons (all editions) gets stupid when it tries to handle a basket of snakes or a bag of rats. And yet, obviously those things are very "in genre" for their respective games, and not being able to handle them because of the limits of variable hit points is a fucking travesty.

Now the thing that makes designing fixed hit point systems hard is not changes of milieu. Having giants or pixies fight it out is trivial, because you just take whatever system you're using for starting characters thwacking each other and add or subtract equal numbers from both sides of the soak equation. The same die roll gives the same moderate wound whether the attack strength and soak were shifted up or down by 3 or 33 points. The thing that's hard is partial scaling. That is, modelling the Iron Colossus is easy because its damage and soak are simply off the scale of the starting characters. The numbers you choose are essentially arbitrary. The Ogre is hard. The Ogre is tougher and stronger than the characters but still expected to face the PCs in combat. Precisely how one goes about handling those attacks that are more punishing but still on the scale is important.

And that's of course where it turns out that non-linear damage transforms from the soak roll are actually really useful. Linear damage roll outputs lead to some variation on the "two shot problem" fairly often. That is: if the Ogre simply does 5 extra damage on every hit and you have 20 hit points and the base damage is 2-20, he's going to take you out in 2 hits about eighty percent of the time. But if the Ogre did only 2 extra damage, he'd still take you out in 2 hits about eighty percent of the time. If instead there's a non-linear transformation (like the old L,M,S,D = 1,3,6,10 system), it's much more plausible to have a bonus that is visible on the RNG that also actually meaningfully changes the average number of hits it takes to drop your opponent.

-Username17

[maglag]

I don't think it is remotely acceptable to have a combat centered game where there is a single roll for attacks. An attack roll plus a damage roll is a basic minimum and not having that has never worked out and will never work out. It just obviously won't.

Yet 3e is the bestest game ever with its hundreds/thousands of save-or-die/lose effects spread everywhere?

[Whipstitch]

That is a very dumb gotcha attempt. 3.x had a lot of dumb spells in it but there is a vast difference between having a system which uses pass/fail saves for things like determining if you slipped in a Grease effect and systems that take that approach for practically everything and are subsequently incapable of tracking attrition or incremental progress.

[DenizenKane]

Yeah, Frank you're right about the non-linear part. I messed and tweaked with everything on the linear model for hours, and it just doesn't work. Alright, back to the drawing board. Also, I think it just helps to have some defined increments in the damage because you can define what amount of damage does what kind of wound/effect.

[maglag]

That is a very dumb gotcha attempt. 3.x had a lot of dumb spells in it but there is a vast difference between having a system which uses pass/fail saves for things like determining if you slipped in a Grease effect and systems that take that approach for practically everything and are subsequently incapable of tracking attrition or incremental progress.

And guess what, grease/color spray/sleep/glitterdust are considered the best spells in 3rd edition for their level. Wizards and clerics just don't care about attrition or incremental progress, they'll just throw the spells that shut you down in one roll (or spells that disable the opposition no matter what they roll like Web and Entangle).

Then even non-caster monsters join in the save-or-die fun. Medusa's stone gaze, Mind Flayer's Mind Blast, all the stuff with fear auras.

Even 3.5 fighters quickly stop caring about their damage rolls because it doesn't matter if you rolled 1 on your weapon die when you're adding a static +Texas to damage that will one-shot the enemy if it hits.

Basically if an attack needs 2+ good rolls to defeat an enemy in 3rd edition, then it's a weaksauce choice and players will ignore it for better stuff.

[Whipstitch]

They're that OP because the action denial is immediate and reliable but that's not just a function how how many dice are involved. FFS, you could rig the DCs so that supposedly level appropriate people get to roll their save 3 times and still have Grease be too damn good.

[maglag]

Not really because of the auto-fail on a natural 1 rule. Even if you crank out your saves, a save-or-die still takes you out 5% of the time unless you managed to get outright immunity. Statistically speaking, chances are that everybody in a party starting at level 1 should die before getting reliable ressurection magic simply because they'll bite the dust to natural 1s against monster save-or-dies even if their save bonus are through the roof.

However if you were allowed 3 saves for the Die part, then that's just 0.0125% chance of auto-failure if your save bonus are up to the task.

[Whipstitch]

The statistical impact of fishing for 1s and 20s isn't completely inconsequential but against level appropriate opposition the effect would be drowned out by setting DC to "fuck off" and you'd sure as shit keep casting them. Again, the problem is still that the shit has a reasonably likely chance of working in one round and melee dorks replace action denial with marching right into haymakers. Beyond that, I genuinely don't see the point of what your question was in the first place since the thrust of it is that you're agree with Frank's point in the present so pointing out that D&D has things which bother people is just sorta hanging there for no reason. People around here feel like D&D 3.x was the best we got, not the the best that there ever could be.