Game Design

Core Mechanics: Hits, Misses, and Armor

Recently I’ve been thinking about attack and damage systems in role-playing games. In Dungeons & Dragons and many other games, there are separate to-hit and damage rolls. This setup allows for easy mechanical distinction between conditions that make an attack more accurate and those that make an attack more damaging. The flip side is that the result of the to-hit roll is generally reduced to a boolean outcome with a good to-hit roll having no effect on the damage of the attack except in the case of relatively rare critical hits. Beyond the number of rolls, another interesting consideration for attacks is how armor is represented mechanically. D&D’s mechanics have armor increase a character’s armor class which makes it harder to hit but has no effect on the damage of a hit. Other game systems have armor instead reduce the amount of damage a character takes when hit or some combination of the two.

Example #1: Dungeons & Dragons

Sprite & Golem: Armor ClassIn D&D, an attack generally consists of two rolls. First, an attack roll is made with a d20 against the target’s defense. For weapon attacks, the defense reflects both the target’s ability to dodge (Dexterity bonus) and how well-armored it is (armor bonus). If the attack roll is equal to or greater than the defense, then the attack is considered a hit and a second roll is generally made to determine the amount of damage. Different dice are used for the damage roll depending on the weapon being used. For example, a dagger might deal 1d4 points of damage while a longsword deals 1d8.

One drawback of having both armor and dodging contribute to a single defense number is that a mechanical miss could be either an actual miss or a narrative hit that is stopped by the target’s armor. For example, a nimble sprite and a slow-moving stone golem can have high defenses for very different narrative reasons. A good Dungeon Master will know to describe mechanical misses differently for those two targets, but there really aren’t any guidelines in the mechanics to help with that distinction.

Example #2: Iron Kingdoms

Sprite & Golem: Defense and ArmorThe Iron Kingdoms role-playing game also uses separate to-hit and damage rolls for attacks. The to-hit roll is a roll of 2d6 + the attacker’s attack rating against the target’s defense. If the roll is greater than or equal to the defense, then the attack is a hit. In Iron Kingdoms, the defense only represents a character’s ability to dodge attacks and does not take armor into account. If the attack is hit, a damage roll is made that is 2d6 + the attacker’s power against the target’s armor rating. If the damage roll is equal to or less than the armor rating, then the attack is still a hit but it doesn’t deal any damage. Otherwise, the attack deals 1 damage for each point that the damage roll exceeds the target’s armor rating.

By moving armor’s effect out of the to-hit roll, this system gives a clearer mechanical distinction between nimble targets and durable targets. A repercussion of that though is that a player may be excited to hit a target on his or her first roll only to then be disappointed by dealing 0 damage as a result of the second roll. While this matches the narrative of such an attack, I know that there are people who really dislike the possibility of those no-effect hits.

Idea #1: Complex Defense

Sprite & Golem: To-Hit and To-WoundOne idea that I’ve had for extending the mechanics used by D&D is using two defense numbers. The lower would be a to-hit number and the higher would be a to-wound number. If an attack roll is lower than the first number, then that is an actual miss, but if it beats the to-hit number but is lower than the to-wound number then it is a hit that fails to wound. In some ways this mirrors the idea of touch attacks and touch AC from D&D 3e, but it extends that concept to add mechanical distinction between misses and ineffective hits for all attacks.

Using this system, you could end up with something a sprite having an 12/15 defense and the golem having a 5/15 defense where the first number determines how hard the target is to-hit and the second reflects the total difficulty to both hit and wound it. While each of them requires an attack roll of 15+ to deal damage, this system means that a roll of 10 misses a sprite entirely while it would hit the golem and simply bounce off of its armor.

While this system preserves the possibility of a 0-damage hit, I think it helps to minimize the effect because it avoids the intermediate successful roll. Rather than having a good roll be negated by a second roll, the player knows that they have failed to deal damage based on just the attack roll.

Idea #2: Single Roll System

The above idea, like the systems for both D&D and Iron Kingdoms, doesn’t make use of the margin of success on the attack roll when determining the amount of damage dealt. That said, it could be extended by removing the damage roll and instead having weapons deal damage based on the attack roll’s margin of success similarly to how the damage roll works in Iron Kingdoms. Different weapons could be differentiated by having a base damage that is added to the margin of success. For example, a great axe could deal damage equal to 6+MoS while a dagger might only deal 2+MoS damage.

By Scott Boehmer

A game enthusiast and software engineer.

8 replies on “Core Mechanics: Hits, Misses, and Armor”

I like your complex defense roll, what might be interesting is adding a custom Hit-but-not-wounded table per monster. If you think about your example, even just HITTING a fairy would probably do something.

As by definition the creature has not been wounded it should just be some sort of impairment. So for example:

Fairy, Hit-Not-Wounded: fairy cannot fly for next round while it becomes oriented
Stone Golem, Hit-Not-Wounded: Last creature who hits stone golem will become target of stone golem’s next attack.

That sort of thing.

Very interesting idea.

You know, I’ve been thinking of narrative house rules a lot lately and i think you’ve solved my combat dilema.
By using the normal system if an attack would hit touch, yet needs to break AC and misses then it’s a deflection or it damages armor.
By using this I can provide better narrative than ” Well you miss, he hits, bla bla bla miss, hit.”
Very interesting concept by the way. Enjoyed reading this.

I was wondering how armor and damage would come into play with your complex defense roll.

Would HIT be a result of high Dex/Agility/Speed and a high WND be a combination of Con/Health/Armor?

I could see a streamlined solution in using a similar method for saving rolls or contest rolls.

Very interesting. Almost has a WFRP feel to it.

For the complex defense, ability to dodge an attack determines the to-hit number. Armor, or any other ability to negate attacks, would then be added to the to-hit number to determine the to-wound number. Assuming a D&D-like system, you’d have something like the following:

To-Hit = 10 + Dexterity
To-Wound = To-Hit + Armor

Damage then could be either a separate roll using a weapon damage die like D&D or based on the margin of success like in the second idea I posted.

In Traveller, you just need 8+ on 2d6 to hit. Cover, prep, movement, skill & talent modify this. Damage is a separate roll, but it is modified by the “effect” in of the attack roll, which is the amount by which the attack roll is above or below 8. Armor simply

Realism in combat should be approached carefully, and lest it slow down play for little benefit. I tend to have the most fun with abstract systems (including 4e) in which a “hit” doesn’t even need to make contact to cause the kind of stress that’s reflected in HP loss.

That’s why idea #2 actually simplifies the system. It puts attack and damage into one roll. It doesn’t slow down play and makes things a little more realistic.

The complication is that right now, in a D&D game, you can figure attack and damage bonuses seperately. It’s possible to have a character that is very accurate but doesn’t do a lot of damage and vice versa. This reduces flexibility in that any add to accuracy is also an add to expected damage. +1 to hit is more valuable than +1 to damage.

I like your analysis, and Idea’s 1 & 2 work well together. In my own system I’ve separated out Miss vs. Damage Resistance (e.g. from armor) as well and there is no damage roll. Instead, as you mention in Idea 2, each weapon has a base damage and is then scaled up according to the success of the hit.

So far it’s worked really well. What ties me up right now is that the defender gets a second roll to resist the resulting damage, and it can add up to a lot of rolls. I can’t shorten it on the damage/resistance end because HP isn’t numeric. Something you said though has put the kernel of an idea for how to do a target Hit number in my mind. I’ll have to explore that a little and see if I can bring the combat rolls back down from 3 to 2 – if my players don’t oppose having their active Defense rolls taken away 🙂

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