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Nerdarchy > Dungeons & Dragons  > Critical Successes and Critical Failures from 1 to 20 in D&D

Critical Successes and Critical Failures from 1 to 20 in D&D

The critical hit is a staple of fifth edition Dungeon & Dragons and is integrated into the game’s mechanics. Critical hits and critical misses have a long history in D&D, and in roleplaying games in general. Many games have had critical miss or critical failure mechanics baked into the rules, but 5E D&D does not. Nonetheless, many gamers who are used to the concept of critical failures like to insert this concept into the game. The results are mixed, and many considerations should be made by a group before making any decisions about tweaking these rules.

The basics of critical success and critical failures

Many RPGs have different systems for determining success or failure. In the case of D&D, the base mechanic is the d20 roll. If critical successes and failures generally occur at the extremes — a 1 or a 20 — this means there is a flat 5 percent chance for a critical success and a flat 5 percent chance for a critical failure.

As pointed out in the video above by Nerdarchists Dave and Ted about critical hits, it can feel more than a little disappointing when you are playing a supposedly expert archer who ends up hitting their allies 5 percent of the time. Other mechanics, such as advantage and disadvantage, can mitigate this, but over the course of the game with an archer firing off shot after shot, it will likely still keep happening that they hit other party members.

D&D was designed with an understanding of this mentality — players generally do not have a lot of fun playing mediocre archers — and discarded the critical failure mechanic altogether. Instead, 5E D&D sometimes uses a result of 1 as an automatic miss or failure, and sometimes it is just another roll and could still result in a success for a competent enough character attempting an easy enough task. These assumptions are in place for all of the rest of the mechanics in the system, and shoehorning a critical failure system in will mean inadvertently disrupting game balance in many places.

To get a feel for what this means, some examples are in order.

Certain race and class abilities, and some feats, allow manipulation of dice mechanics, generally in the form of rerolls. The halfling’s Lucky feature becomes quite a bit more powerful when critical failures are on the table. It’s already a very useful ability that can turn an automatic miss into a hit, but with a critical failure mechanic in play, it can turn a negative result (damage inflicted to oneself or an ally) into a positive result, instead of just turning a neutral result (a miss) into a positive result. The exact same considerations apply to the Lucky feat. It is already arguably one of the most powerful feats, and introducing critical misses into the game would make it even stronger. Consider, too, the diviner’s ability to force dice rolls onto others by way of the Portent ability. Now imagine how much more powerful that becomes in those instances when one of the diviner’s dice is a 1. The more severe critical failures are, the more overpowered that ability becomes.

Examples like this abound, and lead to more than a little silliness. One of the barbarian’s signature abilities is Reckless Attack, by which they can gain advantage on strikes. This means their odds of critically missing drops from 1 in 20 to 1 in 400, from 5 percent to 0.25 percent. Does that sound very reckless to you? It seems a little anti-thematic.

Other shenanigans can occur when a character with a high armor class wades into a sea of mooks and just dodges. If they would need a high roll to hit and they are attacking with disadvantage, it can easily get to the point that they are more likely to hit themselves and their allies than they are to hit their intended target. Admittedly, it is fun to see this trope play out in a kung fu movie where the hero sidesteps a punch and one incompetent henchman smacks another incompetent henchman, but in D&D this type of tactic can become tiresome and tedious pretty fast, both to the Dungeon Master and the other players.

Tactical considerations go beyond just exploiting critical failure mechanics with builds and decision making at the table, but also to the party’s approach to combat situations in general. Getting back to the archer example, if an archer has a chance of hitting their allies, then who really wants to be the ally up front wading into battle?

It’s already a burden to be taking the shots from the giant’s axe, but when your own ally starts hitting you with poorly-placed arrows or firebolts that can make things a little too onerous. It’s even worse when rushing up to face enemies like displacer beasts or invisible stalkers, where your fellow party members may be attacking at disadvantage. This does not completely break the game and make it unplayable, but it does mean a lot of the intended design ideas about combat flow and what kind of builds represent good frontline fighters have to be reconsidered. 

Imposing disadvantage on foes becomes more powerful than being able to sustain hits, and offense will frequently be traded for defense for frontline fighters, which ultimately leads to slower-paced combats that take longer to resolve. Intelligent foes will also be wise to this and will fight more defensively, trying to avoid situations where pure bad luck turns the tables against them, potentially leading to tedious battle scenarios.

critical failures

Yeah, but I still want critical failures!

If, despite the notion the D&D system is the way it is with regard to critical failures for many reasons, your group still wants a critical failure mechanic in place, there are certainly ways to go about that.

The easiest and perhaps lowest-impact way to achieve this is to make the blanket rule that a 1 on a d20 is always a failure, no matter what type of roll is being performed. Class features like Reliable Talent could mitigate this, but it means even a very tough barbarian might still fall prey to a very weak poison spray spell, or a very resilient sorcerer might still have their concentration interrupted by a goblin’s arrow. 

The group will also have to determine exactly what this means in the case of opposed skill checks where both sides roll a 1 or 20, but that can generally be done without too much difficulty. I have been in groups where the initiating side rolls first and, if they score a 1, the defender does not even need to roll. If they roll a 20, the defender has to beat the initiator’s modified result and not get a 1. Playing this way does introduce a little more risk to the players (and to enemy Big Bads), but many groups find this little extra element of risk and bad luck keeps things exciting. Players of older editions will also find this quite easy to accept, since the idea of a 1 always failing on a d20 roll was present in most older editions.

Nerdarchists Dave and Ted mentioned the idea of using the advantage mechanic to allow for critical failures and super criticals. This is also a good way to do it, because these results are infrequent, but could be quite dramatic. In this case, if you roll with advantage and get a 20 on both dice, then you get a super critical.

What that means is up to you, but it could just mean you get a maximized critical hit, or a critical hit where the initial dice are maximized and you can then roll the critical dice and add that to the maximized initial dice. Or it could be a critical hit that induces a status effect (for example, the target is stunned) or allows for a followup attack. On the flip side, if you roll with disadvantage and get a 1 on both dice, it could trigger a critical failure. This could mean hitting an ally, injuring yourself, or inducing a status effect on yourself (perhaps you slip and fall prone) appropriate to the situation.

It is worth mentioning that even this method does put a premium on abilities like aforementioned Lucky feature or feat. It also raises questions in cases such as the Elven Accuracy racial feat from Xanathar’s Guide to Everything. This allows characters with the feat to essentially roll a third d20 when making certain types of attacks with advantage. While there is only a 0.25 percent chance to score two 20s on two d20 rolls, there is 0.725 percent chance to roll at least two 20s on three d20 rolls. This is a small consideration, but it does nearly triple the chance for a super critical. A diviner’s Portent ability could also shift a critical to a super critical or a failure to a critical failure very easily with this type of implementation. Again, this is not a tremendous consideration, but many such minor cases can conspire to skew game balance.

Nerdarchists Dave and Ted touched on a lot of other options for critical failures and successes some of you may enjoy. Personally, I shy away from anything that requires more die rolls on top of the standard ones, especially in combat, where things can slow to a crawl when extra dice start getting entered into the mix. If a natural 1 provokes a second die roll to confirm whether a critical failure happens or not, that just means more time is getting spent rolling. We all like rolling dice; a lot of us would be lying if we said the polyhedral dice absolutely iconic of D&D were not a source of intrigue for us when we first got into the game, and we’d also be lying if we tried to tell you we did not have an inordinate amount of dice that we have collected over the years.

But, when the game is afoot, most of us do not like sitting around watching other people make a succession of die rolls to determine if their character just shot themselves in the foot, and we start to feel self-conscious ourselves when we’re making roll after roll while other players are waiting for their turns.

The critical failure mechanic is actually still there. Do you see it?

In truth, a version of the critical failure mechanic is still in place in a few spots. This takes the form of different results for different degrees of failure. One place where this is obvious is in the saving throw against drow poison, as described in the Monster Manual entry for the drow’s hand crossbow attack. The poison on the crossbow bolts requires a target to succeed on a DC 13 Constitution saving throw or be poisoned. If the target fails by 5 or more, the target is unconscious as long as they are poisoned. Having different outcomes for different degrees of failure or success is part and parcel to many systems. (Alternity is a game that made heavy use of this.) It is also a way to structure critical failures. In a sense, failing the saving throw against drow poison by 5 or more is like a critical failure. It’s much worse to fall unconscious and be poisoned than to just be poisoned.

There are plenty of ways to expand on this concept to make it a more robust system that achieves the goals of a critical failure system. If you wanted to make a quickling variant that moves around so fast and positions itself in combat in such a way that if you miss it by 10 or more on your attack roll you then have to make an attack roll against some other adjacent target of the quickling’s choice (including the attacker!), that would be a great way to slide in a critical failure mechanic in a way that makes sense with a monster’s abilities.

Skill checks could have negative results when the target DC is missed by a wide enough margin, and it would be easy enough to set up consequences for missing the mark by 10 or more for each skill or ability since there are not too many skills in D&D to do this for. Using this system also preserves the idea that an expert at something is not going to critically fail at a mundane task 5 percent of the time, because an expert is unlikely to roll below the target DC for an easy task by a wide enough margin to have a negative consequence for failure.

The downside to this type of mechanic also lies in expediency at the table. It may seem trivial to calculate whether your character missed a target number by a given margin. But it’s often very easy to roll the dice, plus all the modifying dice, and add up your modifier and know you didn’t make the mark, without knowing exactly how much you missed by before doing one more calculation. On any given roll, you might have to only do one extra calculations, but over the course of the session, with several players and the DM all making these extra calculations, it can be a factor, especially for newer players.

And, for the DM, having to remember to ask about the margin of success or failure on a player’s rolls is just another thing to track. Part of the beauty of D&D is the overall simplification of the rules compared to previous editions, and if players are looking for more crunch and calculations, there are other games where that is part of the core mechanics.

Game mechanics and game balance

critical failures

A drow as seen in the first edition Dungeons & Dragons Fiend Folio. [Art by Don Turnbull]

The broader lesson to be gained from investigating tweaks to existing game mechanics such as critical failures or super criticals leading to more variance in outcome or that could be exploited by certain character builds is any time you start tinkering with the rules, there is always the risk you inadvertently create imbalances in the mechanics, specifically because the array of races, class, abilities, feats, spells, and so on have been created with a certain set of core mechanics in mind.

Any change can trigger a ripple effect of unbalanced results, and this sets up a progression of power creep. This is not to say you have to play strictly by the rules-as-written at all times, but it does mean it’s wise to make sure the result you want is really going to be achieved by the changes you decide to implement, and to be aware of all the side effects that are likely to come along with these changes. With many systems, critical failures and super critical possibilities are all part of the core mechanics. With D&D that’s not the case, and it is always good to additionally weigh any potential changes against the intent of D&D being a nimble system that is easy to learn and use, where the rules are specifically designed with playability and fun in mind.

Here’s to rolling a natural 20 on your Insight check to see that your mechanical adjustments all pay off for you and your group.

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Benjamin T. Awesome

Benjamin T. Awesome resides in Los Angeles and enjoys participating in an unmanageably large number of TTRPGs, so much so that it routinely interferes with his Nintendo and board gaming.

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