Mechanic Series: Critical Hits

In the AD&D THAC0 system, a natural 20 is always a hit. What this means is that even if you have a THAC0 of 20, you can still hit a negative AC, such as AC -1. It’s a 5% chance to hit, but it’s still a chance. Many players wanted more, some theories consider a natural 20 to be a true hit, which instantly breaks the system. We don’t really know what hit points are, sometimes a hit really is a hit, and sometimes it isn’t. Since one can go insane trying to pin down what hp are, it is just easier to consider them to be a mechanic of the game kept to the background, and leave it at that; even though, sometimes it isn’t.

Critical Hits is a supplemental rule: however, players and DMs were going to use it anyway, even if the rule isn’t in there. Critical Hits is actually a mechanic first introduced as core to D&D’s very first competitor back in 1975 in a game called Empire of the Petal Throne; now, it wasn’t called “Critical Hit” that term came about later, but it is credited with creating the mechanic which simulated a “Lucky Hit”. Prior to Empire including it, I have no doubt that DMs introduced it into their own loose OD&D games, and it has stood the test of time, but my question is: Is it Fair?

At this point it is also worth mentioning that all d20s are not created equal. You know this, and I know this; but it isn’t something that can be proved. Players will sit there and roll a d20 and find one that doesn’t generate random numbers because of a small imperfection in the die, weirdly enough, this imperfection typically causes a die to roll a 20 more often than 5% out of 100 rolls. It probably has something to do with how the die is manufactured, and its shape; but since the number 20 is the most affected, this tells us that the manufacturer is aware of the problem, and has known about it for a very long time and has been unable to fix it. What is funny about it is that it does balance itself out at the table because all of the other times that you roll a d20, with the exception of the attack roll, you want low numbers. A natural 20 usually signifies an automatic failure, but people still insist on using that d20 that rolls lots of 20s anyhow.

We do have dice that do roll random numbers, but players typically refuse to use these as they are deemed “unlucky”, but whatever; my favorite dice are just as bad as theirs are, so it is all good. But, back to Critical Hits: For years the most preferred method of handling the situation, and the one that is considered core to the optional system, is double damage.

I have two issues with this, first being that there are instances where a weapon automatically gives you double damage anyway. That should be a function of that particular weapon. Other weapons make it a point that if one does roll a 20, than it always does double damage, which implies that this is unique to that weapon, and we should strive to keep it that way.

The second issue that I have with double damage involves math. Lets take a look at what happens when we roll an 8 for damage, and this gets doubled to 16. That one roll takes out more than 1HD from a fighter, 2HD from a Cleric, over 2HD from a Rogue, and 4HD from a Mage. These numbers just imply what happens to characters who were able to roll their Max hp each time, so the real numbers during play are even worse. That, to me, is unbalanced.

Actually, the double damage thing technically isn’t 2e core, but that is how people play it. The true method of handling double damage is to roll 2 damage dice, such as 2d8 which gives you a much fairer number, yes the max damage would still be 16, however that would be a very lucky hit indeed!

Method #2

A natural 20 signifies a bonus attack. It gives your characters (and monsters) a chance of causing extra damage without guaranteeing success. That does present its own problems, slower and more powerful weapons may not be logically compatible with this method such as a musket or a crossbow which takes time to load. While it is still more balanced than instant doubling of the damage die, it isn’t something that really appeals to me, nor is it a universal fix: If one is charging with a lance, a twenty already signifies double damage, and the character charges through the opponents front line; a second attack would mean that he’d be able to turn the horse around and . . . well, you see where I’m going with this. Some weapons only get one attack, and they should only get one attack.

There are some alternatives worth talking about, that aren’t core, but are certainly more balanced and developed.

Method #3

Max Damage

Nothing game breaking about that! Lots of players will go for it as well, as even with the broken double damage rule there is a chance of dealing 2 points of damage, which takes the wind out of your critical hit sails real fast.

Method #4

Roll 2 damage dice, keep the highest

Again, no over-powered death-dealing here, just a simple mechanic that is fast and universal, it doesn’t promise mass damage, but there is a better chance of achieving a more valuable number than normal.

Method #5

Implementing a Critical Hit Chart

These things break the game, and are totally unfair to the players. With a 5% chance of a crit on fair dice, those things might be fun for screwing around but they make long term campaigning impossible.

The typical Hit Chart does damage to a character's stats, and since we don’t fully stat our monsters, this effects only PCs, not even to mention that this mechanic only serves to slow down combat. If you are that bored with your game that you think that you need to implement this kind of stuff to “make things interesting” it is probably time for you to sit down and really evaluate how you play.

Of course, there are times when one does want to implement this kind of system, such as when two fighters meet in one-on-one combat and they really hate each other; a second element of true danger during a very epic level confrontation could be desired by both combatants so that they can just destroy each other. For cases like this, I would suggest temporarily incorporating the system in the Player’s Option: Combat & Tactics handbook which has an exhaustive, and very thorough table system that isn’t fit for every day play, but very appropriate for special cases. It is also worth noting that the Combat & Tactics rulebook has incorporated it’s own definition of critical hits, because when we are dealing with duels like that, we do want to know what each blow is doing; but like I said: It is a system all to itself and should only be used for specific situations; such as the final fight where if the PC wins the duel, he’ll probably retire the character at its conclusion anyway.


I’m sure that there are lots of other methods out there; if you do something different, put it in the comments! We’ll take a look at it. I know in the past I have banned this mechanic from my game, but I am going to implement it again as I’m tired of looking into those sad eyes filled with longing when a 20 is rolled. When we don’t use it, players kind of feel that they are missing an opportunity, which is understandable.


Awesome Dice Blog: d20 Dice Randomness Test; Chessex vs. Gamescience 

So it isn't just me . . .

I also wanted to add these as hotlinks from the comments below:
Castles & Chimeras: Six "20" between 19 and 21 an old-school take on d20 to hit mechanics 

 Fabio Milito Pagliara has his fix to simulate matrix-style mechanics while using a THAC0 system.

Castles & Chimeras: OSR Critical Hit Based on Armor 

Fabio also has a nice article on how armor type can effect the critical hit system.


Anonymous said...

You could be interested in this 2 articles I wrote on criticals

1) Basing the range of Critical on armor

2) putting back the 6 "20" of 1st ed AD&D

sorry to comment as Anonymous, but I am Fabio Milito Pagliara

RipperX said...

Thanks Fabio! I went ahead and added them as live links. I really enjoyed your mathematical approach in both articles, and am very intrigued by the simple and elegant mechanics which you use for different armor types.

I have heard of people using this kind of logic, however their systems were clunkier than the one that you present. As a player, this would force me to play a lot more carefully that I usually do, I like to play unarmored thieves and rely on my DEX bonus, and using long-ranged weapons to keep me out of harms way. If I want to keep from getting crit hits on me I'd have to dungeon delve with at least leather armor. I kind of like it!

Dale Houston said...

Have you seen the Combat Effects in RuneQuest 6? It's not entirely applicable to D & D as the number of effects taken depends on the success of both the attack and the parry, and some other differences in rules. It gives some nice options besides 'extra damage'.

Brooser Bear said...

In battle, any hit you take, can kill you. If you play D&D out of the box, there is no way to kill a high level human or a magical monster that can only be hit with magical weapons with a single arrow.

To deal with this, I came up with a house-rule, that two natural 20's in a row get the opponent out of fight. Notice, I didn't say killed, they just lost a fight. DM's call. That's the arrow through the eye-slit, the blow that deforms the great helm and the knight's brain inside it, a dead infantryman's lucky rifle shot, that damages an antenna or something on a helicopter gunship about to obliterate him, making it fly away.

The other mechanic I use is that if a player character takes 1/3 or more of the hit points in one blow, have a chance of being knocked down, knocked out, and going into traumatic shock, until someone administers first aid.

Traumatic shock is an almost magical and a horrifying thing, that makes the injured unaware that their faces are torn off, their brains are sticking out and that their guts are in their laps. It allows people to function despite massive damage. People run on broken legs and pilot aircraft for (amazingly) long seconds with chests destroyed by bullets and hearts no longer beating. Take someone, who is calm and awake, and tell them that the back of their head is blown off or that you can see their brains, and people will become aware of their injuries, go into shock, and DIE.

For this reason, I have several built in pathways that escalate the damage a la critical hit. Applied to both, monsters and players.

RipperX said...

RE: W Dale Houstan

I am not familiar with Rune Quest 6. I haven't played any RPGs except Dungeons & Dragons. I own a few, my favorite being Call of Cuthulu 5e, however as sad as it is, I've never played it. Gamedays are far and in between at my table, so we stick to what we love.

RipperX said...

RE: Brooser

I have mixed feelings in regards to PC violence. My games are a lot darker than what I imply in my blog, I've a large background in horror and crime fiction, and that does carry over in my personal game, however that is something that I've always just done!

On one hand, I think that a characters body is the property of the player. They are the one who imagines what this person looks like, and I like to leave it at that.

However, I do get gruesome with my descriptions. The world itself is my domain and it is a vicious place. My villains are horrible people, I enjoy creating culture shock, and death can either be realistic or stylized depending on how I feel at the time. I have never left this up to chance via the dice, it has always been on purpose.

I will deform a PCs body and leave a mark if that character either drops below 0hp, or has to roll a system shock check. I will describe hits if I feel that they happened, or to bring the players back into our make-believe world because I feel they are too focused on mechanics. I've never used Crit Hits to do this, I've always done this with intent and on purpose, never randomly. Perhaps that is considered by many to be unfair, but so far my players like it!

If there are 6 people at the table, we are all playing our own games, I understand this. I don't want to force 1 vision down their throats, while my violence is intensely brutal, I still prefer to keep it stylized and movie-like.

Red Sonja witnessed lots of horrible things, but we all know that if she took a mace to the knee than this wonderful story would be over, and nobody wants that.

Brooser Bear said...

Touche, Ripper! There are six players at the table, each in the world of their own, and it is the job of the DM to herd them together so that Player Agency might appear like a magic spark among them.

You misunderstood my examples, they were not from the game, they were from real world. I am not running a gothic or a horror game, I run an overall positive wilderness frontier game, where I developed game mechanics to have the wilderness adventure accessible to low level players and make it largely survivable, unless players ignore warnings and get in too deep.

Combat is violent, and the consequences of combat are more disturbing than combat itself. Little girl's mother gets killed by raiders, the child is screaming inconsolably, and the players have to figure out what to do with her. I had players and NPC's gravely injured and sliding toward death. I don't dwell on gore. The most violent example of combat, that ultimately was too much for the player and he quit was as follows: Players were caught in the open field crossing it to the Tower. A bunch of goblin wolf riders were riding the players down. Players formed a shield wall with the lightly armored thieves and magic users running for the protection of the ruined wall.

The riders impacted with the Goblin lances (do 1d6+2 damage when used off wolf back). Female fighter took a critical hit that killed her. I rolled and rules that it was goblin lance getting between the edges of the shields, piercing her chainmail, and breaking off deep in her chest.

I told players that the character screamed and went down with a broken lance in her chest. The next round another player rolled a 1, a fumble, I deemed that he slipped in her blood and fell next to her, losing his weapon (rolled result). I described the scene to him and the player decided to give the first aid to the fallen female fighter. He was failing (in the heat of the game, player forgot to check to see if she was alive or dead). I had him roll a perception check and he noticed that another goblin was riding him down as he was on the ground on all fours. Player was racing against the time to cast the entangle spell to stop the wolf charging. He cast successfully at the last minute, the wolf rider failing the saving throw, the player not being able to get up in time, crawling away on all fours with the rider trying to reach him..

It was a hot melee scene, I don't think that it was particularly violent or unreasonable. I run an adult game for thinking players. Some people like it, and get uncomfortable at times, others quit. I had a player throw a flask of oil into a barn, where he believed to be goblin raiders, instead he burned a bunch of peasants. I had a role playing encounter between the villagers, the village priest, and the players. The guilt and discomfort were palpable. The guilty player was never in any physical danger from the peasants, he was a man at arms and part of a knight's retinue. The player on the spot was red faced and angry, he wasn't having fun, but he finally made amends by promising to feed the surviviors for the rest of their lives, and I think that the player felt better.

Like I said, a game of decisions and consequences for adult players. I am not sure how you'd consider this.

RipperX said...

What would I consider that? Like an exciting game! Dangerous goblins? Why the new generation would think that you were cheating! Goblins are just xp walking around waiting to be collected, the very idea that they can kill you is almost unheard of among the untested masses.

I think that you have made your case wonderfully; I will tell you that one of my greatest pleasures is graphically describing the effects of a curative spell. One cringes more when you have to go through the motions. Casting those things in a way that reduces the painful effects takes some time to learn. It is the little details that make all DMs unique.

Brooser Bear said...

True, each DM is a story teller, and is an artist as such. There is no right way or the wrong way to do art, so long as it has the desired effect. I think that D&D 5th Edition went in the direction of more story telling, witness the simple advantage/disadvantage dynamic, where the DM becomes the bard, who uses polyhedral dice instead of a stringed instrument.

Dangerous Goblins? Bah-Humbug! They are regular Goblins, just as any others, merely intelligently led ones! And what do we call weapons, folks? Force Multipliers!

Fabio Milito Pagliara said...

@Ripper X
thanks for the praise and for the links

yes the idea is to give something more than just a AC bonus for donning armor w/out changing the rules of the games

The Dale Wardens said...

Good stuff. I like critical hits and give them both ways. I do give players a saving throw v. critical hits if they are wearing a helmet (which also penalizes their hearing, -and vision if it's a great helm.) My current campaign is a slow leveling, low magic, Game of Thrones style where I have told the players to expect physical degeneration from their fights. It has made them very aware and clever about how they engage in combat.

David S.
Minnesota, USA

RipperX said...

Very interesting David S., I've always found helmet rules to be interesting. Are you suggesting instant death from a head shot unless you're wearing a helmet? STIFF! But I like it.

BTW I added you to my Blogroll, your site is freaking awesome!

The Dale Wardens said...

Thanks Ripper,

I don't really use a location system unless someone receives an injury. The the presence of the helmet just gives the player a roll to negate the enemy's crit. I have played around with a rolling critical hit system that someone told me about from Hackmaster.

I'll give you the quick rundown of combat in the campaign. A critical hit does double dice damage. A rolling crit die is rolled and if you get a 19 or 20, you do another die and get another rolling hit, this time at 18-20 being success. This continues increasing by +1 until the rolling hit fails. A helmet (on a PC) gives a saving throw to negate an enemy's crit. Enemies do get rolling crits. I don't typically give monsters a save v. crits (maybe for a boss?) One player got 2 rolling crit successes ...once. Otherwise I do not recall any successful PC rolling crits. A brigand got one once, and it did not turn out too bad for the PC. The fear and excitement of the rolling crits is present, but in practical terms it has not happened too often.

There are no resurrection or raise dead spells in the campaign. If the player reaches 0hp they get a temporary injury. If they reach -3hp they get a saving throw v. serious injury. If they reach -10hp they get a saving throw v. Death. If they succeed they live! (But, they are out of commission for a long time, receive a -1Con and a permanent injury.) The injuries are based on the table in the Player's Option Combat and Tactics book. Only one player has reached -10...and he done that 4 times! His guy is much diminished from his original roll, including loss of his left arm (he was a bow and two weapon ranger.) He still plays the character and actually enjoys the developments. His guy is winded easily (permanent level of encumbrance and -1" move), has his left arm in a sling, (little use of and -2 str and -2hp) and is -4con from his original rolls. He spent 8 months recovering at a monastery, so he has spent a lot of time on the sidelines Everyone has a reserve character, so he played his backup quite a bit. He is a grizzled warrior now who has seen the face of battle and bears its scars.

As I mentioned we are going for a Game of Throne/semi realistic(ish) feel to things.


There is no resurrection in the game.

The Dale Wardens said...

One last thing that has recently occurred to me, but I have not implemented yet is using critical hits to damage player equipment. After receiving a critical hit, perhaps it does damage to their chainmail, which will now need repair.

RipperX said...

David S. This is one of those things that really surprise me. I was always led to believe that players hated that style of play, but you have presented it in a way that forms a counter argument, and you aren't the only one to do so.

I have dealt with guns in one of my previous campaigns, and you are right, a basic crit can be pretty common, but a nasty one which is less common does take the game into unplanned places which are surprising for everyone (DM included) and quite pleasing, and it does balance itself out. In our 1890's campaign, which lasted a couple of years, we only had one high crit hit and it totally changed the dynamic of the game.

A crit resulting in AC loss until it is repaired is also very doable, I had originally included that in the article, but it got kind of crazy and I try to keep my articles kind of short and easy to digest, but I would like to touch on the subject, as it is a fun mechanic, but it can get complex, and I am rather windy.

The Dale Wardens said...


I think if the players know what they are getting into (permanent injuries and fatalities) it helps. For our theme it makes sense. Far less has happened than I thought would so far, but there is still the expectation in the group that the situation will change. Everyone is wondering who will be the next one to take a grievous injury.

It has made the group ask each other this sentence on numerous occasions, "Do we really think we have to fight these guys?"

I'd like to see something on damaged equipment sometime when you get the mood for an article!

2nd ed!


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