Simple Attacks & Grapples

A Song of Ice and Fire Chronicle Starter from Green Ronin Games
Cover art for A Song of Ice and Fire Chronicle Starter from Green Ronin Games

I’ve been working on different ways a combat system could function, and I’ve constructed something I’m pretty happy with. It borrows heavily from both OD&D, and material I’ve read on Untimately.

Each class has a “Combat Target Number.” Anytime a character wishes to take offensive physical action against something, they roll a twenty sided die. If their roll on the d20 is equal to or higher their CTN, then the action succeeds. As each class levels up, their CTN becomes gradually smaller. Modifiers to the CTN are rare, which allows it to be very simple. A single number written on the player’s character sheet, which they must roll against.

Most characters will also have an Avoidance Score. This is typically a very small number, between -3 and 4. For most characters, their avoidance will be the same as their dexterity modifier; though if the character uses a shield, that will also add +1 to their AS. Again, modifiers to AS are rare, which keeps it simple. Any time a creature with avoidance is attacked, the AS is added to the attacker’s CTN.

Armor does not benefit a character’s avoidance score. Instead, it functions as a type of damage resistance. Each type of armor will have a die associated with it. As a simple example, lets say that leather armor uses 1d4, chain armor uses 1d6, and plate armor uses 1d8. Any time an attacker rolls a successful attack, they must then roll their damage dice against the defender’s armor dice. The value of the armor die is then subtracted from the value of the attack die, mitigating or even eliminating the damage dealt to the target.

My primary goal here is simplicity, which I think I’ve achieved. The player need not roll 1d20 + BAB + Strength + Weapon Bonus + Relevant Feat. They don’t even need to roll 1d20 + [Bundled Attack Bonus]. As silly as it might sound, taking two numbers and figuring out which is bigger is easier than taking two numbers and adding them together. I also like how the system keeps both the attacker and the target mechanically engaged. While determining the success of the strike, the player and GM need to communicate the CTN and the AC. While determining damage dealt, the player and GM are rolling dice opposed to one another.

You may have noticed that the CTN is to be used anytime “offensive physical action,” is taken. That’s because it would also be used similar to Pathfinder’s Combat Maneuver roll. The attacking player rolls against their CTN plus their target’s AS if they’re attempting to kick sand in their eyes, or disarm them, or grapple them, or whatever. Grappling in particular is traditionally complex and unwieldy. From 1st edition AD&D’s “Non-Lethal and Weaponless Combat Procedures“, to the system in D&D 3.X which was so complicated I literally kept a flowchart at the table at one point. Pathfinder’s combat maneuver system is a huge step in the right direction, but I think it can be simpler still.

When attempting a grapple, the attacker rolls against their CTN + their Target’s AS as normal. If they succeed, then they’ve got their hands, legs, tentacles, or whatever on their opponent. The attacker then makes a strength check (Roll 1d20. Equal to or under STR is a success, over STR is a failure). The defender may either roll a strength check, or a dex check, whichever they prefer. Whoever succeeds by more gets to pin/push/hold their opponent. If the two players tie, they are stalemated. If both players fail, success goes to the defender.

A basic example of play might proceed thus:

Fighter “I’d like to attack the orc. My CTN is 11.”
GM “The orc has an AS of 2, so you’ll need to roll a 13 or better.”
Fighter [roll] “A 15! That’s a success, so I’m rolling my damage die, 1d8.”
GM “The orc only has chain armor, so he’s rolling a 1d6 for defense.”
[Fighter and GM both roll their dice.]
GM “The orc rolled a 4.”
Fighter “That’s not bad, but I rolled a 6, so he still takes 2 damage!”
Rogue “Me next! I’ll get him with my throwing knife. My CTN is 14, so I need to roll a 16 or better here.” [Roll] “17, Success! Rolling my 1d6 damage die…”
[Fighter and GM both roll their dice.]
GM “I’m afraid the orc’s 3 beats your 2.”
Rogue “Fucking fuck. I wanted his gold. >:(”
Wizard “That really just leaves me. But my spells are gone, and my staff only deals 1d4 damage, so there’s a good chance I couldn’t hurt him even if I hit. I’m going to try to tackle him so the other players can hit him more easily next round.”
GM “Alright, you can try that. But you’ve got a CTN of 16, so you’ve gotta roll an 18 or higher to succeed.”
Wizard [roll] “I actually did it! I got an 18! Just barely!”
GM “Alright, but you’ve still gotta make your strength check. The orc is much stronger than he is agile, so he’ll be using his strength to oppose you as well.”
Wizard [roll] “Woo! I got a 10, that’s just under my Strength of 12!”
GM “Ah, but the Orc got an 8, which is way under his strength of 16. When you leap to tackle him he knocks you aside with his arm. You’re now sprawled on the ground behind him.”

There are a few complications to this system which I’ve omitted here. Both strength and dexterity do have a role to play, as do various positioning and circumstance bonuses and penalties. But this is the basic structure of the system, and I would be interested to hear thoughts on it.

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19 thoughts on “Simple Attacks & Grapples”

  1. Just found your blod about a week ago and have been working m way through all of your post, just wanted to say im facinated with the conecpt of this system and will probably attempt to implement it with my group in the next week or so. Thanks for the amazing insight.

    Carder McNally

  2. I like this. You’re basically making modern day THAC0 under another name though. I like the armor as damage resistance, but you will need to take a look into literally everything in the CRB to see how the new rule will interact.
    Pathfinder as a system is such that everything in it is made to work together, and that makes house rules wonky at times. You’ll need to think of what a touch attack entails under the new system (I can think of at least one quick fix), you’ll have to look at each individual offensive spell and see how that fits with what you want, etc.
    So yeah, I like the system, but you just created loads of work for yourself.

    1. This rule has nothing to do with Pathfinder.

      I mean, at one point in its development, PPFLLS was meant to be a Pathfinder hack. But while working on the attack rank stuff, I realized I wanted to change far too much for a simple hack. Rocksfall is a new game from the ground up.

  3. CTN

    I like this. I’ve toyed with variations on this constantly, but this is a good version.

    That said, it is the same as THAC0, fundamentally – one target number modified by Defense. The advantage here lies in using addition instead of subtraction.

    Weapons and Evasion

    One of the main things I wanted when designing my combat system was to model the fact that your weapon defends you – you may want to consider that a man with a sword is way harder to hit than an unarmed man, and make weapons a part of the evasion score. Or not.

    Armour as Damage Reduction

    For Spells and Steel I considered using dice for armour, but ran into a few problems.

    1. More dice rolling slows things down.
    2. No dice are small enough.

    d8 of damage reduction is HUGE. You’re going to find it almost impossible for two guys in plate to end up killing each other. Consider a guy with a 75% hit chance who does d8 damage – he’s doing 3.375 damage per round, on average. But the plate is soaking up 4.5 damage per round on average! His average DPR just went down to zero.

    Maybe that’s what you want, but it’s something to consider. I ended up going with simple 1,2,3 points of damage reduction for cloth, chain, and plate armour. Easy to remember, and easy to do.


    From my experience in medieval combat training, grappling isn’t something you choose to do. “Choosing” to grapple an armed opponent is the same as choosing to die – they *will* strike off a limb, head, thrust your chest, etc. etc.

    Grappling is something that just happens at the right moment in a fight – so I’ve handled grappling as a successful critical hit. On a crit, you can do extra damage, or grapple.

    1. CTN
      The system is very similar to THAC0, but I don’t think it’s fair to call it the same. The switch from negative numbers to positive numbers is non-trivial, in my opinion. THAC0 also used armor as avoidance, whereas I’m using it as damage reduction.

      The primary similarities is that attacking ability is defined by class, and a d20 is used.

      Weapons and Evasion
      As a European sabre fencer, I’m well acquainted with the block and parry. So I can agree with you that the importance of a weapon as a defense mechanism in combat is important.

      That said, I’m fine with a certain level of abstraction in the game. The weapon already confers the player with the ability to deal damage. It’s difficult to figure out a good way to add a weapon bonus to avoidance. Perhaps the simple explanation is that weapon blocking is part of the dexterity bonus to avoidance.

      Armor and Damage Reduction
      I’m aware the numbers probably don’t work out right now, which is why I haven’t committed myself to anything yet. There are a number of possible ways to deal with these issues, such as heavier armor reducing dexterity avoidance (possibly down into negative numbers), or reducing possible weapon damage.

      That’s an interesting system, and I can see the value in it, but it’s not one I’d be interested in implementing here. I like a game where unusual combat tactics are a viable option. Is it realistic? No. But it does keep the players trying new and interesting things, which makes combat fun.

      1. Functionally, it’s the same as THAC0 – roll a d20 against a target number defined by your class modified by a static defense.

        Compare that to Harn, say, that uses a d100 roll to judge degrees of success for the attacker and defender, and then looks up those results on a table.

        I would also point out that armour has a negligible effect on your ability to fight, so penalizing peoples defense for wearing it isn’t very realistic. If you care about that, not everyone does.

        1. I think you and I would define the phrase “functionally the same” quite differently. But I’m not really concerned with making this mechanic different just for the sake of making it different. I would much rather have a simple mechanic which is derivative of what came before it, than a pointlessly complex mechanic.

          And you are correct, I don’t care about realism. I would even go so far as to say that the idea of games needing to be ‘realistic’ is one of the single worst things that has ever happened to games. So many games have had the fun completely drained from them because of a slavish devotion to an ultimately unattainable ideal of realism.

  4. I really like this. I think it is more streamlined than THAC0. It is actually really similar to a combat system I’ve been working on. I think I shall take this and modify it a bit to fit my other rules.
    One thing, I think the avoidance modifier will favor Strength classes over dexterity classes. For instance a fighter with a shield and plate armor would have an avoidance of say 3-4, he would also have heavy armor which is 1d8 of damage reduction. A rogue on the other hand would have an avoidance of 4-5 and only 1d4 of damage reduction. I think that with these stats you have the ability to do some fun things with a rogue, but I think it would make the rogue very weak in it’s current form. Maybe if you gave dexterity classes an automatic +1 or 2 to avoidance it would work better.

    Also, you could add some distinction between blocking avoidance (armor or shield) and reflex avoidance. with this system I really like the idea of a rogue as someone that is really hard to hit, and hits hard, but has low damage resistance and low HP.

    1. Armor only affects the defense roll, though. Only dexterity and the use of a shield modifies Avoidance.

      I’m sure the numbers will need to be tweaked a bit, though. The system is new, and hasn’t been tested yet.

      1. I assume you meant ” Armor only affects the damage roll”.

        Sure, but at the end of the day the damage roll and the attack roll combined give you average damage per round.

        Spencer’s point is that your damage per round will be way, way lower against someone wearing plate with a low dex than against someone wearing leather with a high dex.

        That’s because modifiers to the damage roll count for far more than modifiers to the attack or defense values.

        Look at a Fighter, no dex bonus, plate, and d8 longsword vs. rogue with +3 dex, leather, and same weapon. We’ll say they’re both 1st level, and have the same CTR of 15 (dunno what you’re going for in that regard, but it doesn’t matter much here).

        Fighter ADPR: -2.05 (actually negative, because of the armour – most rounds he will do 0 damage).
        Rogue ADPR: -3.375

        In reality, it would be even more skewed, as the Fighter would likely have a higher CTR, as well as a Strength bonus.

  5. Why go so far as to have the defender role dice. I think it would be easier to set armor at a flat number? You already have the defender’s Dex add to the difficulty of the CTN, so why not have the “damage reduction” of the armor be a constant?

    1. Because if someone has a set damage reduction of 6, then a weapon with 1d4 damage will never ever hurt it.

      However, if the attacker rolls a 4 and the defender rolls a 3, then maybe the blade managed to get between the armor’s plates. It’s less likely, but it’s not entirely impossible.

            1. What if critical hits negated the defender’s defense roll? That would simulate hitting the one weak spot on an otherwise heavily armored opponent (reminds me of Smaug…)

              1. I really like that! It actually simulates weak spots effectively. Way to awesome.
                Also, reaaaaaaaaallly looking forward to RocksFall.

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