Alternative Critical Hit and Fumble Rules Adaptation

[Mith]

Hello. I am trying to port an idea I read that related to 1st Edition D&D (I believe) that implemented THAC0 attack matrices to 5e. If I should change the tag on this or move the thread to a different forum, I can do that.

The idea is from an old Dragon article I read that got rid of the natural 1 and natural 20 critical fumble and hit. Instead, if you hit an enemy your chance at a critical hit was the difference between the AC you hit and the target AC. For example if you rolled to hit AC 2 and the AC was 5, you have a 3% chance at making a critical hit. If you missed, the difference between your roll and your target AC became your critical fumble chance. So flipping the numbers in the previous example would give you a 3% fumble chance. The confirmation of your critical hit or fumble was determined by rolling percentile and rolling the number or under. This idea works in that as the character gains levels and better equipment, they become less likely to fumble and more likely to land critical blows.

Now I am actually looking at implementing this idea in 5th edition, but first analysis makes it seem like the chance for a hit becomes too high, especially if you use the high end monsters that have huge bonuses to attack. And this is without assuming magic weapon bonuses.

My question to the Old School D&D crowd is would implementing such a attack matrix system in 1st Edition D&D have resulted in high critical hit chance as well, or are the design assumptions between the two editions too different to try and port the idea over?

Thank you for your thoughts.

[LibraryOgre]

The Mod Wonder: I moved this to 5th edition, because that's your primary thrust of inquiry; it really comes down to 5e probabilities.

I don't know the 5e numbers well enough, but it's an intriguing system... any hit, save on-AC hits, can be critical, while any miss might be a critical miss.

[PhoenixPhyre]

Hello. I am trying to port an idea I read that related to 1st Edition D&D (I believe) that implemented THAC0 attack matrices to 5e. If I should change the tag on this or move the thread to a different forum, I can do that.

The idea is from an old Dragon article I read that got rid of the natural 1 and natural 20 critical fumble and hit. Instead, if you hit an enemy your chance at a critical hit was the difference between the AC you hit and the target AC. For example if you rolled to hit AC 2 and the AC was 5, you have a 3% chance at making a critical hit. If you missed, the difference between your roll and your target AC became your critical fumble chance. So flipping the numbers in the previous example would give you a 3% fumble chance. The confirmation of your critical hit or fumble was determined by rolling percentile and rolling the number or under. This idea works in that as the character gains levels and better equipment, they become less likely to fumble and more likely to land critical blows.

Now I am actually looking at implementing this idea in 5th edition, but first analysis makes it seem like the chance for a hit becomes too high, especially if you use the high end monsters that have huge bonuses to attack. And this is without assuming magic weapon bonuses.

My question to the Old School D&D crowd is would implementing such a attack matrix system in 1st Edition D&D have resulted in high critical hit chance as well, or are the design assumptions between the two editions too different to try and port the idea over?

Thank you for your thoughts.

5e tends not to have absurd hit bonuses (that's bounded accuracy), but there's still some issues. Looking at the MM--the Tarrasque is at +19 to hit, and normal people have ACs around 20 by those levels. Ancient Red dragons are +17 to hit, high end demons are +14/+15.

A quick bit of math shows that against your average squishy, a tarrasque will crit (using your idea) about 20% of the time and miss never. That's pretty brutal. Under the standard method, it will hit 95% of the time and crit 5% of the time. That's a 5% + ~2x(15%) = roughly 35% increase in damage done.

Note--that will also make weak creatures (who can still hit reasonably well when they get lucky or in packs) much more prone to fumbling. It will also require a gear treadmill to maximize your attack bonus/AC.

Overall, I'm not a fan.

[Aett_Thorn]

I would say that the ideas behind this might work out, but it would mean that classes and subclasses that work on crits would be disproportionately hit by these changes. For instance, the Champion's expanded critical range, and the Barbarian's extra damage die, are both balanced based off of the current crit chances (1 in 20), so any change to that might make these classes stronger or weaker, depending.

[Unoriginal]

Hello. I am trying to port an idea I read that related to 1st Edition D&D (I believe) that implemented THAC0 attack matrices to 5e. If I should change the tag on this or move the thread to a different forum, I can do that.

The idea is from an old Dragon article I read that got rid of the natural 1 and natural 20 critical fumble and hit. Instead, if you hit an enemy your chance at a critical hit was the difference between the AC you hit and the target AC. For example if you rolled to hit AC 2 and the AC was 5, you have a 3% chance at making a critical hit. If you missed, the difference between your roll and your target AC became your critical fumble chance. So flipping the numbers in the previous example would give you a 3% fumble chance. The confirmation of your critical hit or fumble was determined by rolling percentile and rolling the number or under. This idea works in that as the character gains levels and better equipment, they become less likely to fumble and more likely to land critical blows.

Now I am actually looking at implementing this idea in 5th edition, but first analysis makes it seem like the chance for a hit becomes too high, especially if you use the high end monsters that have huge bonuses to attack. And this is without assuming magic weapon bonuses.

My question to the Old School D&D crowd is would implementing such a attack matrix system in 1st Edition D&D have resulted in high critical hit chance as well, or are the design assumptions between the two editions too different to try and port the idea over?

Thank you for your thoughts.

That seems way too complex and game-stop-to-make-calculation for 5e, at first glance.

Though I'm not sure what's your goal, maybe if I got that I would understand why you want to implement it.

Also, do you want to apply that to both PCs and NPCs?



5e tends not to have absurd hit bonuses (that's bounded accuracy), but there's still some issues. Looking at the MM--the Tarrasque is at +19 to hit, and normal people have ACs around 20 by those levels. Ancient Red dragons are +17 to hit, high end demons are +14/+15.

A quick bit of math shows that against your average squishy, a tarrasque will crit (using your idea) about 20% of the time and miss never. That's pretty brutal.

Yeah, those monsters are meant to be brutal, but not that much.

[Hyde]

I sort of like it, in that it's different from 20=crit, etc. But I feel like it could go sideways pretty quickly. I'd be loathe to pile on a bunch of riders to make it manageable, for simplicity's sake. I have a feeling it would end up in a lot of "boss fights" ending in more TPKs, as the legendary monsters have a tendency to eclipse the party's AC with their attack rolls.

[Pex]

Aside from the fact I loathe critical fumbles, to be more blunt, I don't want to do algebra every time I attack to figure out percentages and then roll percentile dice. I don't object to the concept of complexity, but when there's no fun in how it works the desired goal is lost in the shuffle.

[Mith]

Thanks for the replies so far.

@Mark Hall: Thanks for moving. I started their to see if people familiar with the system the concept started in would know if this was otherwise balanced by other factors within the system that I did not account for. If there is some system insights that I am not aware of, I could adjust to make things work better and not be so freaking brutal at high end games.

To clarify the concept, the table has all the math done on level up or switching out gear, so I do not think the concern about math during play is a problem. Then again my experience is that THAC0 attack matrix isn't a bad concept, just implemented poorly so maybe my "no more math than usual" is too much math for other people.

For talk about high level monsters and critical hits, that is what I noticed in my analysis as well. I still like the idea of a variable critical system instead of a flat percentage to demonstrate different attack skills and better weapon effects. I do not like the static 5% auto miss and 5% "interesting effect" regardless of character power or fancy equipment (magic +X weapons).

As for fumbles, I personally am not the fan of the "crazy fumble system", if I were to implement the system it would along the lines of "fumble first attack get a penalty". No "cut off your own head" features. And the nature of character growth is that these should occur less often as the character levels up, unless facing a difficult to hit opponent (high AC).

[Unoriginal]

There is no "fumble first attack get a penalty" or "cut off your own head" features in 5e. If you roll a 1, you fail your attack, if you roll a 20 you succeed your attack (and generally get an assorted bonus), that's it.

[Mith]

There is no "fumble first attack get a penalty" or "cut off your own head" features in 5e. If you roll a 1, you fail your attack, if you roll a 20 you succeed your attack (and generally get an assorted bonus), that's it.

The example given was more a reference to other fumble features that usually appear in such fumble systems. The idea with this is that a starting character with a lower combat skill system would have a chance to fumble an attack (which would usually be a miss, and at most would be an advantage to the enemies next attack against you). As the character improves, their hit bonuses (representing combat skill), improves to the point that they do not fumble their attacks other than just missing, and they do critical hits more often.

The original idea I was going for was to take the idea from the post linked in the OP and have the effects of the critical hit scale based on how much you exceed the target AC roll. This means when you land a really hard hit it does more than just double damage dice.

However, I am skeptical about this system being worth the effort without serious overhaul in how attack modifiers scale, as it does make high end fights be "Whoever gets hit dies, aside from the barbarian who'll stick it out to round 2." Which isn't quite what I am going for here.

[Joe the Rat]

Something that might help the Critical Tarrasque would be to require a decent die roll before you start counting crit points... or a sucky roll for whiffs.

I'm falling back to the MEGS system for inspiration. Part of the math for the system expects extra results on the effect table, based on your roll on the action table... but you only count the "above needed" shifts if you rolled above average. (13 on 2d10, in this case). So Mr. T has a +19 to hit, but still needs to get at least... oh, let's say an 11 on the die before we start checking for crits.

The flip on this example doesn't quite work - the tarrasque would have to roll wellbelow average to have a chance of fumble - so you're checking every time it misses.

I'd be more inclined to keep the 1-and-20, and use the over/under as a modifer on the crit tables.

[Mith]

Something that might help the Critical Tarrasque would be to require a decent die roll before you start counting crit points... or a sucky roll for whiffs.

I'm falling back to the MEGS system for inspiration. Part of the math for the system expects extra results on the effect table, based on your roll on the action table... but you only count the "above needed" shifts if you rolled above average. (13 on 2d10, in this case). So Mr. T has a +19 to hit, but still needs to get at least... oh, let's say an 11 on the die before we start checking for crits.

The flip on this example doesn't quite work - the tarrasque would have to roll wellbelow average to have a chance of fumble - so you're checking every time it misses.

I'd be more inclined to keep the 1-and-20, and use the over/under as a modifer on the crit tables.

Yeah, that's probably the best option without building my own system. What I would probably do is that your AC roll still matters, so that on a roll of a 1 if you can still hit, you do, and on a roll of a critical number (20 for most attacks), you roll percentile to see if you do anything fancier with your hit.

I believe that the improved critical still counts as automatic hit if you roll a 19 (or 18 at 15+), or do you still have to meet the target AC? If so, I think I would still like the probability of the critical hit table to be that non Champions rarely maximize the rider effects they add to critical attacks.

[PhoenixPhyre]

I believe that the improved critical still counts as automatic hit if you roll a 19 (or 18 at 15+), or do you still have to meet the target AC? If so, I think I would still like the probability of the critical hit table to be that non Champions rarely maximize the rider effects they add to critical attacks.

Improved critical does imply that any of the affected rolls are automatic hits. It doesn't trigger riders that trigger on a natural 20 (like a vorpal blade's decapitation thing IIRC), but critical hits are only critical hits if they hit, and it does guarantee a critical hit.

[BoringInfoGuy]

One thing to keep in mind when considering altering the basic 20 = critical hit / 1 = auto miss system is that it is already does the players more harm than good mechanically.

Players face a variety of opponents, many of which are not a significant threat individually. A crit scored on one of these opponents may take it out of battle a round sooner than normal, but they were there to be killed in combat anyway.

When a player recieves a critical hit, that eats up resources. If the PC drops to zero, then the other players have to spend some resources to bring back the character, or finish the battle short handed. Which could mean the combat takes more rounds to finish, increasing the chance that something else will go south for the party

The resource drain can then carry on to the next fight, and the next, until the party has a chance to recover.

That is before you add in any mechanics to improve criticals based on how easy it was to hit the target. Players still end up with getting most of their crits against foes that were meant to drop easily anyhow, while the BBEGs end up with an effective bonus both to avoiding and dealing critical blows through typically having higher bonuses than the party.

Despite being balanced against the players, landing a crit is enough fun that most players would be opposed to removing the system entirely. (Myself included).

TL;DR
A player dealt critical hits effects one battle.

A player received critical can effect multiple battles through resource loss.

Therefore critical hit systems give a disadvantage to the players overall.

Modified critical hit systems tend to exasperate the situation.

[Mith]

Improved critical does imply that any of the affected rolls are automatic hits. It doesn't trigger riders that trigger on a natural 20 (like a vorpal blade's decapitation thing IIRC), but critical hits are only critical hits if they hit, and it does guarantee a critical hit.

That is what I thought, and it is how I would rule. However, I recall some pretty weird discussions about this a while ago that made me question my memory of the text.



A player dealt critical hits effects one battle.

A player received critical can effect multiple battles through resource loss.

Therefore critical hit systems give a disadvantage to the players overall.

Modified critical hit systems tend to exasperate the situation.

I did read the entire thing, but this is a good summary of the whole post. And is also a valid point.

The problem with the crit system I have is that heavy hitters hit a lot harder, and the resources that counter it (AC, HP, healing, etc.) do not grow enough to be an effective counter without making everything damage sponges. Even if the crit table was all extra effects and just double damage dice, it occurring as often as it would at higher level would be a bit much.

I still like the idea, but I guess it wouldn't be a beneficial change.

[PhoenixPhyre]

I still like the idea, but I guess it wouldn't be a beneficial change.

Stinks, don't it? I've had many "good" ideas that turned out to be impractical to implement or had horrible knock-on effects. Still hurts to give them up, though. :smallsad:

[Mith]

Stinks, don't it? I've had many "good" ideas that turned out to be impractical to implement or had horrible knock-on effects. Still hurts to give them up, though. :smallsad:

Yeah. It's frustrating with this one because the idea makes sense in my head, and would probably work not too bad, if it was for humanoids vs. humanoid combat, where everyone is within a certain distance from each other for combat. But when you are looking at the very high end of the system, it breaks down.

Maybe if I am ever running a low - mid level, humanoid only campaign, I may come back to this idea. Then anything that is a brutal heavy hitter that breaks down this system is given the terrific depiction they deserve.

[PhoenixPhyre]

Yeah. It's frustrating with this one because the idea makes sense in my head, and would probably work not too bad, if it was for humanoids vs. humanoid combat, where everyone is within a certain distance from each other for combat. But when you are looking at the very high end of the system, it breaks down.

Maybe if I am ever running a low - mid level, humanoid only campaign, I may come back to this idea. Then anything that is a brutal heavy hitter that breaks down this system is given the terrific depiction they deserve.

For real heavy hitters, especially NPCs, I tend to just give them a trait or ability that lets them hit like a truck (or do triple criticals, or whatever is most fitting). There's no more NPC/PC transparency, so you can make those limited-scope modifications without trouble. For PCs you can give custom boons (like feats, except as rewards).

[Mith]

For real heavy hitters, especially NPCs, I tend to just give them a trait or ability that lets them hit like a truck (or do triple criticals, or whatever is most fitting). There's no more NPC/PC transparency, so you can make those limited-scope modifications without trouble. For PCs you can give custom boons (like feats, except as rewards).

Fair enough.

Thanks for all the help with the breakdown on this idea. When I did my first analysis of the idea, I figured that it would be a no go, but it always helps to have other perspectives on it.

[PhoenixPhyre]

Fair enough.

Thanks for all the help with the breakdown on this idea. When I did my first analysis of the idea, I figured that it would be a no go, but it always helps to have other perspectives on it.

Not a problem. I use the forum as a sounding board myself, so I'm always willing to help where I can.

[BoringInfoGuy]

I did read the entire thing, but this is a good summary of the whole post. And is also a valid point.

The problem with the crit system I have is that heavy hitters hit a lot harder, and the resources that counter it (AC, HP, healing, etc.) do not grow enough to be an effective counter without making everything damage sponges. Even if the crit table was all extra effects and just double damage dice, it occurring as often as it would at higher level would be a bit much.

I still like the idea, but I guess it wouldn't be a beneficial change.
Thank you.

It would probably be a bad idea for the standard Heroic Fantasy tone of D&D.

But if you were thinking of running a more lethal survival-horror themed campaign, then it could be appropriate.

In general, I tend to be leery of house rules made simply for the sake of tinkering. But it can be a great way to help reinforce campaign themes.

(Just make certain you have player buy in before investing too much time.)

[KorvinStarmast]

Aside from the fact I loathe critical fumbles, to be more blunt, I don't want to do algebra every time I attack to figure out percentages and then roll percentile dice. I don't object to the concept of complexity, but when there's no fun in how it works the desired goal is lost in the shuffle. This.

Dear OP: we messed with Crits and complex variations on that for some years in the early decade of D&D. 5e's KISS principle is simply better than all of that other stuff. Been there, done that, recommend against.

Best wishes and happy gaming in any case.

[Pex]

Stinks, don't it? I've had many "good" ideas that turned out to be impractical to implement or had horrible knock-on effects. Still hurts to give them up, though. :smallsad:

I know the feeling. Way back when in 2E I tried many rule shenanigans. I redid the cleric sphere system. I've tried converting D&D spellcasting into Ars Magica spellcasting. It was hard, but I finally did learn to KISS - Keep It Simple Stupid. A house rule here and there is fine, but if you need to write your own handbook something is wrong. Having learned my lesson, it's now a bothersome trait to me when the DM can't stop fiddling with the rules. It's not enough he has lots of house rules. He has to keep changing them between game sessions, often changing how to play the game. This is not a 5E thing, though I have one such DM now and one once before. A past 3E/Pathfinder DM did it constantly, and it was driving me up the wall. At least he also fiddled in my favor allowing me to use a 3rd party sourcebook for spells for one campaign and Tome of Battle for another soon after it was first published.