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Were-Sandwich
2006-11-12, 02:11 PM
I'm trying to completely revamp the d20 system for use in my games. I'm turning it into a skill based system, rather level based. What I really need help on is the combat system. I want to include an opposed Parry/Dodge type system, similar to the one in Inquisitor, with armour providing DR. I'm having trouble balancing it. No matter what I try, I can't seem to balance it. It always comes out in favour of the attacker. At the moment I have 3 main ideas:


Parry is a skill, a-la NWN, based on Dex
Parry is your Defence Bonus (from UA) plus your Dex modifier
Parry is an opposed BaB check. As with reiterative attacks, successive Parries are at a decreased value. This makes TWF a very good defensive choice
So, ideas.

beachhead1973
2006-11-12, 04:16 PM
i wanted something like this in my Envy the Dead setting, but it was too complicated and so i just scrapped it.

what i did instead was gave each weapon that could be used to parry a (-) or (+) bonus to AC when used in fighting defensivly.

as envy the dead also uses action points this permits people to use both offensive, defensive and movement option in a single 10-second turn.

all actions/skills/processes have requirements in either real time (turns) like how long it takes a grenade to go off or (AP) how long it takes X chracter to perform Y action

TheOOB
2006-11-12, 05:20 PM
I strongly suggest agaist this. There are dozens, even hundreads of skill based PnP RPG systems out there, too many to even attempt to name here, and some of them are very good systems (heck I play shadowrun every chance i get). Instead of making a huge change to the d20 combat system, just play with another system that allready works the way you want.

The d20 system is more so then almost any other system based on rules, and many of the core rules are very hard to change without completely reworking the system. Combat in d20 is made to be as streamlined as possible, you roll a dice, and see if you hit, it's quick, it's easy, and dozens of books of materials have be written assuming thats the rules you are following.

I'm not saying it can't be done, I'm saying trying another system would save you a hell of a lot of work.

Golthur
2006-11-12, 11:06 PM
If I had to vote, I'd go for the Defense bonus approach - it's easier to balance than the other approaches - and, it's always on.

Adding extra parrying options through fighting defensively and total defense would also help for those times when you just can't get hit.

The hard part of balancing it is that you've got two factors to balance:

1. BAB vs. DB. Fighting characters' BABs typically advance +1 per level. Using the scale from d20srd.org, even a totally defense-focused character (using progression "D") is going to be about 8 or 9 points short to make it a 50/50 hit chance on the primary attack at 20th level. This doesn't include feats which permit a character to boost their attack roll (Weapon Focus, etc.). If you're using armour as DR, you're going to have to provide characters a way to make up those points along the way, or change the scale. This is even more necessary if wearing armour limits your DB.

2. Secondary attacks. This also skews toward the attacker, as they gain multiple attempts to strike (albeit with ever decreasing attack bonuses). This may be taken care of if you solve (1), since the next attack in the sequence will have 25% less chance of striking. That is, if DB was set to make your single BAB 50/50, your hit probabilities would end up being 50%/25%/5%/5% for all four iterative attacks. This still ends up with the attacker doing, on average, 85% of their normal damage every round.

EDIT: And that's why higher-level monsters have such huge natural armour bonuses, and any wizard spells that require attack rolls either use touch attacks, or use the CL+ability bonus as the attack roll :smile:

Were-Sandwich
2006-11-13, 11:15 AM
I'm trying to make a skill based D20 mainly to see if it can be done. I like the idea of a Parry system for some reason, as it makes combat more...realistic, for lack of a better word. My idea sort of combines the Defence Roll, Defense Bonus and Armour as Damage Reduction variants, all into one. So, any ideas on how I could do it better?

Golthur
2006-11-13, 11:47 AM
That's fair enough. You can balance d20+DB vs. d20+BAB. Then you can advance the DB in a similar way to how you're advancing BAB. It does make for more rolls in combat, but it's pretty much an opposed skill check, which fits well with the normal mechanics.

The key thing to figuring it out right is how much damage you want a skilled attacker to be able to do, on average, each round, against someone who's:
Lousy at defending themselves.
OK at defending themselves.
Good at defending themselves.
Really, really good at defending themselves.

You'll also want to figure out how much you want concentrated defensive action to influence it as well (e.g. fighting defensively, or total defense).

You'd have to express this as a percentage of their normal damage; e.g. lousy: 70%, OK: 50%, good: 30%, really, really good: 10%.

Then you can figure out what your DBs need to be to make that happen with multiple attacks at each level. EDIT: Another way around it is to eliminate multiple attacks/round - that is, a round is one second (or less), and represents a single attack opportunity.

Another concern is balancing it in low-magic vs. high-magic. When I houserule combat (and I do, a lot :smallwink:), I usually balance for no/low magic, and just make sure that I provide equal opportunities for offensive and defensive magic across the board. That way, if there's a +3 sword of uberslashing, I make sure that there's a +3 sword of uberparrying around, as well. The core D&D combat system is balanced for essentially one type of offensive enhancement, and multiple types of defensive enhancements, but it forces you to use the WBL guidelines otherwise everything goes out of whack.

Were-Sandwich
2006-11-13, 12:18 PM
Hmmmm. I'm still a little hazy on how I'm handling BaB. At the moment I'm thinking of a Skill for each weapon category (Light Blades, Heavy Blades, etc), with BaB for that weapon category based off that. OBviously I'll have to play around with Max-Ranks some more.

Golthur
2006-11-13, 12:29 PM
Are you allowing multiple attacks like standard? Or just one shot per skill check?

EDIT: The reason why I ask is that it dramatically alters how you handle the DB check. Multiple attacks are inherently tipped toward the attacker, which means your max ranks on your DB need to be that much higher to compensate for it.

It's also possible you could allow multiple attacks, but only trigger them when your skill check is sufficiently higher than the parry (i.e. a sort of auto-riposte). This would take some work to figure out in its entirety, obviously.

Telonius
2006-11-13, 12:33 PM
First: Shields no longer contribute to AC. The "Shield Other" spell and other such abilities function as a +1 Tower Shield. (This will make sense in a minute).

Attack roll: d20+BAB+STR (or dex for finesse-able or ranged weapons)
If the attack is lower than the AC, it fails. If it's higher, it has a chance of success.

If there's a chance of success, the defender has a chance to parry. (Except on threatened criticals; even if the threat is not confirmed, these are not subject to parrying). If the defender is using a shield, they can choose to raise it against the blow. The shield takes full damage (possibly breaking it) if the damage exceeds hardness, and the defender takes half the damage that the shield does (nonlethal).

If the defender chooses to parry, roll a Dexterity check. A person wielding a weapon designed for parrying (rapier, sai, quarterstaff, improved unarmed attack, or whatever the "Real-Life Weapons Experts" say is a parrying weapon) gets a +4 bonus on this roll. If this check exceeds the attacker's attack roll, the attack is successfully parried.

EDIT: New Feat: Improved Parry
Prerequisites: Dex 13+
You gain a +2 to attempts to parry an attacker's blow. When attacking, treat your attack roll as +2 for purposes of an enemy attempting to parry your blow.

Further Edit: Not sure how well that'd work into your skill-based system. If you ditch "armor as DR," you could keep it with a few tweaks: if your (whatever attack roll) is greater than your (whatever defense roll).... etc.

If you do keep the armor as DR idea, I'd make one suggestion. If you have a roll at all for defense, that seems to suggest to me that the person is somehow skilled at dodging, moving around, or otherwise avoiding getting hit. To put another parry roll on top of that seems a little redundant to me.

Were-Sandwich
2006-11-13, 02:07 PM
That seems...complex. Workable, but complex.

What I have so far, is Skills are split into Major and Minor Skills.Minor Skills are Spot, Jump etc, whereas Major skills are stuff like Heavy Blades, Light Blades, Parry etc. They take 4 skill points to buy the first rank. Attack rolls are opposed skill checks (Relevant Attack Skill vs Parry). Parry is a dex-based skill, keeping Dex a defensive skill, with any modifiers going to AC going to parry, except armour and natural armour bonuses, which go to DR.

Thats a rough outline.

XtheYeti
2006-11-13, 02:37 PM
Parry=Combat Expertise...kinda obvious

Golthur
2006-11-13, 02:50 PM
I did some more thinking, and multiple attacks very seriously change your basic balance, so you're going to want to consider this issue seriously.

Suppose we have two characters, each of which has maxed out their BAB and DB skills (and the two are kept on the same scale).

For simplicity, lets assume we use the same +5->+6/+1 multiple attack progression.


The base chance of d20+BAB beating d20+DB if both are equal is 50% (it's basically d20 vs. d20). Each +1 on the BAB side increases the odds by 5% towards their side, and vice versa for DB.

So, assuming 50% chance of hitting, that basically means 50% of their normal damage = 0.50*1.00*damage for hitting, and 0.50*0.00*damage for not hitting :wink:

{table="head"]BAB|DB|Avg Damage/rd (as % of normal)
+1|+1|50%
+2|+2|50%
+3|+3|50%
+4|+4|50%
+5|+5|50%
+6/+1|+6|50% + (50%-5*5%) = 75%
[/table]

See the massive damage upswing at +6/+1? This is because they have a 25% chance of hitting with their second attack, even though the BAB and DB are equal.

In order to make the equivalent 50% at +6/+1, the DB would have to be about +8 or +9, or, conversely, you'd have to change the multiple attack formula.

Were-Sandwich
2006-11-13, 03:00 PM
But for the second attack, you'd still be parrying at +6. How does this increase damage? My head hurts?

Golthur
2006-11-13, 03:07 PM
Because the attacker still gets a second chance to hit. It doesn't ever eliminate his chance to hit, it only reduces it.

I'll walk it out a little more clearly.

First attack: +6 vs. +6. It's a d20 vs d20, the +6s cancel each other out, so 50% chance of hitting, right? Thus, on average, delivering 50% of the attacker's normal damage - delivering full damage for when they hit, and no damage when they don't hit.

Second attack: +1 vs. +6. This tips the odds 25% (5*5%) towards the defender's side. Thus, the attack has a 25% chance of hitting. Again, on average, delivering 25% of the attacker's normal damage - delivering full damage when they hit (25% of the time), and no damage when they don't hit (75% of the time).

The first attack and the second attack are independent of each other. So, on average, the first attack does 50% of their normal damage and the second attack does 25% of their normal damage. Net result: 75% of their normal damage per round.

Were-Sandwich
2006-11-13, 03:17 PM
So, how does it work out in standard d20?

Golthur
2006-11-13, 03:21 PM
If you had defense bonuses that increased with level, about the same, really. Your AC in standard d20 is what you'd get if you took a 10 on your defense roll. Armour helps a lot at low levels, but not so much once the BABs get beyond the best armour your class can reasonably wear. EDIT: The damage is also skewed somewhat by the always-hit-on-20 rule, which means every attack delivers on average 5% of your normal damage. So, someone with 4 attacks against an AC they can't hit, would still, on average, deliver 20% of their average damage a round. It's just that most rounds they wouldn't hit, and a few they would (one in every 5 rounds they'd hit once). This also doesn't count criticals, BTW.

They're counting on you taking feats (e.g. Dodge), and getting items to boost your AC up that 1 point per 3 levels (or so) that you'd need to compensate for the multiple attacks.

EDIT: In standard D&D, where you have no defense bonuses, they're counting solely on items, feats, and class abilities. Thus, the WBL guidelines.

If you don't do that, well, squish :biggrin: - as anyone who's played in a low/no magic campaign without changing the rules has found out.

EDIT Pt. 2, the Return of Edit: I don't think I was very clear, so I'll rephrase. It seems like (with my back-of-the-napkin calculations) a rough guideline to keep things at 50% average damage/round would be: +1 DB per BAB, with an additional +1 DB per 3 points of BAB (or +2 for 6 if you want to be more accurate). This applies both to regular D&D (in which case add 10 for the matching AC), and to your proposed skill system - assuming a +6/+1 multiple attack progression. Thus, a defender against a +15 BAB "should" have a +15 + 5 = +20 DB, or AC 30 to keep everything the same. Even this will likely creep towards favouring the attacker by one point every 12 levels or so. Adjust up or down from there if you want a different base %ge instead of 50%. This doesn't count the 5% always-hit (which isn't an issue in a skill-based system), nor criticals. I'll likely do more accurate calcs later when I have time :wink:

The other side of this, of course, is the average damage vs. hit points curve - which is a whole other ball of wax :tongue:

EDIT Pt. 3, Edit's Revenge: OK, I've had time to play around with this, and my back-of-the-napkin calc for the 5% difference per point of BAB/DB difference was a bit off (and it's very noticeable at difference values more than 10), but the general principle is still the same. Here's the Real TableTM:

{table="head"]BAB - DB|Hit %||BAB-DB|Hit %
-20|0.0%||+20|100.0%
-19|0.1%||+19|99.9%
-18|0.5%||+18|99.5%
-17|1.1%||+17|98.9%
-16|2.0%||+16|98.0%
-15|3.1%||+15|96.9%
-14|4.5%||+14|95.5%
-13|6.1%||+13|93.9%
-12|8.0%||+12|92.0%
-11|10.1%||+11|89.9%
-10|12.5%||+10|87.5%
-9|15.1%||+9|84.9%
-8|18.0%||+8|82.0%
-7|21.1%||+7|78.9%
-6|24.5%||+6|75.5%
-5|28.1%||+5|71.9%
-4|32.0%||+4|68.0%
-3|36.1%||+3|63.9%
-2|40.5%||+2|59.5%
-1|45.1%||+1|54.9%
0|50.0%||0|50.0%
[/table]

So, to figure out your average damage for +6/+1 BAB vs. a +6 DB, look up the (+6)-(+6) value (50.0%) and the (+1)-(+6) value (28.1%), for a total of 78.1% of average damage each round of attacks. To push this to around 50%, the DB would have to be around +9 or +10.

For BAB +15/+10/+5 vs. +15 DB, you'd get 50.0%+28.1%+12.5% = 90.6% of average damage each round of attacks. To push this to around 50%, the DB would have to be around +19 or 20.

This will also change depending on whether attacker or defender wins on a tie.

Were-Sandwich
2006-11-14, 10:58 AM
OK, what about each weapon skill gives a synergy bonus to Parry whilst you wield one of those weapons. Tumble could give a synergy bonus too.....

About Fighting Defensively and Total Defense, how about: Fighting Defensively lets you take 10 on Parry checks. Total Defense lets you treat any Parry roll of less than 10 as 10.

Golthur
2006-11-14, 11:13 AM
OK, what about each weapon skill gives a synergy bonus to Parry whilst you wield one of those weapons. Tumble could give a synergy bonus too.....

About Fighting Defensively and Total Defense, how about: Fighting Defensively lets you take 10 on Parry checks. Total Defense lets you treat any Parry roll of less than 10 as 10.
I'd go for that, make it +2 or +3 (or so, but vary from weapon-to-weapon), and allow Weapon Focus, etc. to add to it; maybe add a few more parry-related fighter feats that add +2, as well (and can be taken about once every six levels or so). That'll probably work out about right to keep pace with the BAB and multiple attacks at 50% of average damage.

If you want less than 50% for a skilled defender (and want to proportionally decrease it for others), just add a base +2, +4, whatever you find is appropriate to all defense checks.

Re: fighting defensively/total defense. Not sure about this one. Taking 10 doesn't make you any more competent, it would just give you an average roll.
It actually doesn't make your defense any better - just more predictable. Minimizing the lowball rolls doing total defense sounds good, but you'd have to run it through to see if it plays out well.

Were-Sandwich
2006-11-14, 11:47 AM
How about Fighting Defensively is just +2 to Parry?

Golthur
2006-11-14, 11:52 AM
I can't see why most of the regular options (e.g. fighting defensively, Combat Expertise, and so on) can't carry over straight.

True, the hit probabilities are non-linear because of the two dice (instead of just one like normal), but the difference isn't huge until you start getting out past a relative difference of +/-10.

Were-Sandwich
2006-11-14, 11:57 AM
OK, I see your point. I''l just map over the AC bonuses as Parry bonuses. You know, one day I should probably write all these idea in one place.

Golthur
2006-11-14, 12:18 PM
Yeah, I do that. I have one big document where I put all my rule revision ideas. I'm up to about 250 pages now :smile:

How are you handling ties? Same as opposed skill checks - highest total modifier wins? What about ties on that front?

EDIT: If you were going to change any of the standard defense options, I'd actually increase them, overall. A 1-point BAB-DB difference is usually less than 5%, so a +2 is actually less effective in the new system than a +2 would normally be (typically around 6% compared to the normal 10%).

Were-Sandwich
2006-11-14, 02:49 PM
Hmmm. I'm not very good at statistics. I was thinking of ripping off CoC d20, where each character chose a "profession" or origin, which decided their class skills, to stop people having ranks all over the place.

Captain van der Decken
2006-11-14, 02:55 PM
If you're having a parry system, are you intending realistically easy death? i.e. I shoot you, you die.


How does this work with ranged attacks? Would be had to parry say, a shuriken.

Were-Sandwich
2006-11-14, 03:19 PM
Despite the name, Parry includes dodging and weaving as well. Its a generic defense skill.

Golthur
2006-11-14, 04:56 PM
Hmmm. I'm not very good at statistics. I was thinking of ripping off CoC d20, where each character chose a "profession" or origin, which decided their class skills, to stop people having ranks all over the place.
I'm not too bad at stats :wink:

I'd probably take that idea, and go with one more. Make each character have a background (i.e. where you're from, how you were raised), and a profession (i.e. what you do now). Each of the two together determine "class" skills.

You'll also need ways to permit characters to acquire more "class" skills through feats or something similar, as well, in lieu of multiclassing.


If you're having a parry system, are you intending realistically easy death? i.e. I shoot you, you die.

That's what I was talking about with the second part - your damage vs. hit points balancing. You can certainly do what Captain van der Decken's talking about - go for some variant of wound points, and, if you get hit :eek:.

You'd probably need to make it harder to hit if you're doing this, though, since one serious hit=likely death. If you want lots of combat in your game, you might not want to do this. People tend to want to talk their way out of things when there's a serious risk of death attached to fighting :smile:.

If you want to get really crazy, add vitality to the mix, but use it as a constant drain - e.g. every time you attack or parry, you lose vitality points. When you've got no more left, well, you're stuck.

Were-Sandwich
2006-11-15, 11:44 AM
When I said 'realistic' I didn't mean 'realistic'. It always bugged me that only your offensive abilities increased with level, whilst your defensive ones didn't.

On skill selection: I have the skeleton of a system. Each character picks a background (naval, farmer, guttersnipe, soldier etc) and a profession/fighting stye (assassin, martial arts, soldier etc). All of your background skills are 'class' skills for you, and are mostly Minor Skills. Your profession/fighting style skills are mostly major, and work like Skill groups from Iron Heroes. For example, lets say Martial Arts gives you Unarmed, Monk Weapons, Light Blades, Tumble and Concentration. Putting 1 point in Martial Arts gives you 1 rank in Unarmed, Monk Weapons, Light Blades and Tumble.

Experience is giving me a real headache, as are Feats, HD and Saves.

Golthur
2006-11-15, 12:08 PM
When I said 'realistic' I didn't mean 'realistic'. It always bugged me that only your offensive abilities increased with level, whilst your defensive ones didn't.
Yeah, me too. In my home rules, I use incrementing defense bonuses, with combat maneuvers you can take to increase them further. If you're a really defense-focused warrior-type, you can pretty much opt not to be hit. Of course, you're going to be useless at actually delivering any damage.


On skill selection: I have the skeleton of a system. Each character picks a background (naval, farmer, guttersnipe, soldier etc) and a profession/fighting stye (assassin, martial arts, soldier etc). All of your background skills are 'class' skills for you, and are mostly Minor Skills. Your profession/fighting style skills are mostly major, and work like Skill groups from Iron Heroes. For example, lets say Martial Arts gives you Unarmed, Monk Weapons, Light Blades, Tumble and Concentration. Putting 1 point in Martial Arts gives you 1 rank in Unarmed, Monk Weapons, Light Blades and Tumble.
Sounds good. I'd likely make bookworm-types have to advance their combat skills separately, too, whereas their bookwormy-type-skills they can do the same as the fighters do.


Experience is giving me a real headache, as are Feats, HD and Saves.

You're trying to do away with XP and character levels entirely? Tall order, but I can offer a few ideas:
You can use something similar to the BRP Call of Cthulhu "check" system for character advancement. Basically, whenever you use a skill in a way significant to the plot (DM fiat, more or less), the DM can let you "check" it - if a skill's already checked, you don't get two. At the end of the adventure, each "check" acts as an opportunity to increase the skill. You basically roll, and if you roll more than your current value in the skill, you increase it by some number (usually a bigger number if you only have a few ranks, and a smaller number when you have a lot - BRP Cthulhu uses d10 - the "tens" digit of the % skill value, but this isn't suitable for you). This makes it progressively harder to increase skills that you are very good at already. I'd probably also give out "free" checks at the end of adventures or for RP, to put on whatever skill you want.
Some saving throws can increase with relevant skills. For example, your Reflex saving throw can increase with acrobatic skills (tumble, jump, balance, etc.). Not sure how this would work for Fortitude or Will, though.
HD would purely be a function of combat ability, if you're using a more-or-less standard HD system. The problem with balancing it is that the bookwormy-guy's combat abilities may not advance too much, putting him very far behind on the HD front.
Feats, well, maybe you could save up "free" checks for them? Every X "free" checks, and you can buy a feat from someone who can train you in it?


My current headache is skill-based magic :wink:

Were-Sandwich
2006-11-15, 12:22 PM
Hmmmm. Could work. I'll have to think on it.

Yakk
2006-11-17, 01:32 PM
First note: In standard D&D +10 to -10 goes from "auto hit" to "auto miss".

With two d20, that takes +20 to -20. In other words, bonuses are about half as useful.

How about we run with that?

At +11 offence, you get a second attack at +1.
At +11 defence, you get a second defence at +1.

This makes the spike in effectiveness less of a spike.

You can also double up other bonus' -- like all melee weapons can have both dex and strength mods added to their to-hit.
...

You don't have to lock people out of multiclassing. If all rolls are contested double-d20 rolls, +2 is about as good as +1 is under standard D&D.

So have your caps be addative.

Change class/cross class to "easy" and "hard" for your class.

Easy skill: +2 cap per level in the class.
Hard skill: +1 cap per level in the class.
Half skill: +1 cap for every 2 levels in the class.

Longsword is a Easy skill in Fighter, Hard skill under Rogue.
L 5 rogue L 5 fighter.

5*2 + 5 = 15 longsword cap.

L 10 fighter
10*2 = 20 longsword cap.

Flanking might be a Hard Rogue skill (adds +1 to hit and +1 damage to sneak attacks per level).

Flanking might be a Half Bard skill. So a L 6 bard L 3 rogue would have up to 6 points in Flanking.

Done right (with magic skills for magic users), every class could get the same number of skill points/level.

And now your character "class" is determined by your skill point caps in each skill. :)