D20 version of Riddle of Steel's simultaneous combat?

In The Riddle of Steel, when two people fight, each 'round' has two volleys. You have a dice pool that has to last you the whole turn.

For instance (and highly simplifed), Luke has a dice pool of 12, Vader of 14. Luke has initiative, and decides to go first. He attacks Vader, and applies 4 dice to his attack. Vader applies 6 dice to defense. If Luke gets more successes, he gets a hit in. Vader then applies his remaining 8 dice to attack, and Luke uses his 8 dice to defend.

This is made more complex because you can choose to simply parry (which just stops an attack), or counter (which gives you fewer dice, but if you succeed you get a bonus to your next attack). And there are weapon damage ratings, armor resistance ratings, different hit locations, and so on.

What I'd like to do is work in the simultaneity aspect of combat in a d20 ruleset, instead of using a dice pool. Any ideas of how to do this?
 

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I'm not trying to port this into 4e, or even 3e. Rather, I want to create a sort of hybrid system for my players, who are comfortable with d20 basics, but don't like the artificiality of 4e combat powers. Also, I'm not a fan of rolling lots of dice and adding them up.

So, what, say we give PCs a combat rating, with, say, 10 as a baseline. You roll d20, and add some portion of that. Your opponent likewise rolls d20 and adds some portion of his CR for defense. What's the probability here look like?
 


So, what, say we give PCs a combat rating, with, say, 10 as a baseline. You roll d20, and add some portion of that. Your opponent likewise rolls d20 and adds some portion of his CR for defense. What's the probability here look like?

Well, if both are starting with "10" as a base, it doesn't really matter... the number total you arrive at might be higher than starting at zero, but it's not changing the probability. At least, not as I understand things.

Note: I'm not mathematically inclined, so I don't actually do probability things. Instead, I rely on other people doing the work for me. :D

One thing that should help you out for at least some of your questions is Small Roller. It's a handy probability program; it might not handle every kind of dice rolling thing out there, but it covers what I need. And as a bonus, unlike a lot of the probability calculators, it'll give you a nice graph to look at as well (from the Display menu option you pick Probability Chart).

You can find Small Roller here:
SmallRoller -- A Dice Roller/Probability Calculator

Now for this particular question, it's answered in a couple of places:
Math of 2DX Dice Systems | Giant Battling Robots
and
Opposed Roll Probability - RPGnet Forums

The blog shows you the graph for opposed rolls (that downhill thingy) which is basically 2d whatever. Note: if you use Small Roller and simply input 2d20 you'll get the same looking hill but inverted. The key is that the blog graph starts at 100% and goes down, where Small Roller starts at 0% and goes up.

The rpg.net link has the important bit about the bonus minus bonus.

Now, I actually used the Opposed d20 rolls for about a year; I was using Everstone which is a BESMd20 based game, and one of the things it has is Opposed Rolls for combat.

My players seemed a lot more engaged, because they were actively opposing my critter attacks. Individual rounds probably took somewhat longer because there was a lot more dice rolling going on overall, but it didn't _feel_ longer to me as a GM and like I said, the players seemed to be more engaged.

Trying to do what it seems like you're doing... hmmmm... the problem is that you're running up against a decent chance of bogging things down with more bookkeeping.

Bearing in mind that I personally tend to favor going simpler (in part because I'm a lazy GM), I think the first thing I'd look at playing with is the BAB. Effectively, it becomes a pool of points that can be spent in either Attack, Defense, or a combination.

For example, a 13th level Fighter has 13 points that could be put towards actually hitting the target, defending yourself against a hit or a combination thereof. Maybe the attack gets 7 points applied to it and the defense gets 6.

Now, I myself would be inclined to use BAB that way, not the actual full Attack Bonus; you know, what you'd get from Weapon Focus and Weapon Specialization for example. "Static" bonuses like that (and weapon enhancements, etc) would be straight up pure bonus that I'd be inclined to add on to the Attack side of things.

But there's nothing really stopping you from letting people use the whole range of their attack bonus instead of strictly relying on BAB.

Should Reflexes add to the pool? Personally, I'd be inclined to say it depends on the kind of maneuver that's being attempted as to whether or not Reflexes would add.

For an interesting twist, you might consider doing a "half-your level" bonus (basically every 2 levels you get a +1 bonus) that's applied to either Attack, Defense, or Parry.

I'd be inclined to handle Parry along the lines of "For every [x] you beat your opponent by, you inflict 1 point of damage". Yeah, it might not be strictly "accurate", but it means there's now a potential 3rd option besides simply hunkering down and taking the blows, or going ape on someone. If you want to make it a more attractive option, it could be a base of 1 point of damage and then weapon enhancements, weapon properties (like flaming) etc add in.

I think there's room to play around with Attack, Defense, and Parry (with Reflexes tying into Parry) to develop some different fighting options.

The danger here of course is going in the direction of creating "maneuvers" that cost x number of points and then have y benefit. I think that's simply over-complicating things; a certain percentage of people might be interested in it, but I think practically speaking, it just becomes one more thing to try and remember about the rules, like Bull Rush and all that.

If you're wanting a greater "complexity", then tapping into all 3 of the saves and using those as targets instead of just AC might be the way to go. So an attack against Will might be something where you're inflicting relatively superficial wounds that are painful and distracting. Reflexes attack would be where you're trying to keep your opponent off-balance and you're again going for quicker attacks, rather than substantial damage. Fort attack would be straight up trauma and endurance. Doing armour as DR might be more appropriate for this style of system though.

Does any of that help, spark ideas, or even relate to what you're thinking?
 

Here's a riff on Basic D&D (and, in a way, Star Wars d6!).

Each round:

1. Declare actions for the round.
2. Roll init.
3. Melee/Readied Ranged Attacks
4. Movement
5. Ranged Attacks
6. Melee
7. Spells

1. Everyone says what they are doing for the round.

2. You roll init.

3. If anyone's in melee right now, they can attack (assuming they said that was what they were doing!). If someone has an arrow nocked or a crossbow cocked, they can loose it now.

4. Everyone makes their movement now. OAs and whatever fire off.

5. Ranged attacks go off. They may draw OAs.

6. If anyone ends up in melee that hasn't already attacked (or, in 3E, maybe the rest of your Full Attack, or extra attacks in AD&D), they can do so now. This would be like a charge I guess.

7. Spells fire off now.


As always, init determines the order of actions in each combat segment. If you won init, you can make ranged attacks first (though not before movement), maybe taking out the other archers before they can get their arrows off.

edit: Check out this blog post, RW: http://www.lumpley.com/comment.php?entry=455 Does that make sense?
 

I suppose instead of a dice pool, you could use a modifier pool? So taking your example, Luke has +12 total modifier and Vader has +14 modifier. Round one Luke attacks and adds +8 to his roll. Vader adds +7. Next round Luke uses his last +4 and Vader does another +7...
 


Sorry for not checking this thread before now. Plenty to read. I've sort of decided that my goal for now is to see if I can recreate the best duel of all time:

[ame="http://www.youtube.com/watch?v=SuK-34rLkOs"]YouTube - Light Saber Duel - Empire Strikes Back.[/ame]

Here's how it works in normal D&D:

Round 1 - Posturing. Vader takes a total defense to test Luke's skills.

Round 2 - Luke attacks, misses. Vader readies another total defense to piss off Luke.

Round 3 - Luke attacks, misses. Vader bull rushes Luke to piss him off some more. Luke falls over. Vader backs off.

Round 4 - Luke stands, advances (too far to attack, too close to charge). Vader backs off again on total defense.

Round 5 - Luke attacks, misses. Vader attacks, misses.

Round 6 - Attack, miss. Attack, miss. But Luke realizes Vader is much better than him.

Round 7 - Luke backs off (why? no real reason to in the D&D rules), readies an attack. Vader approaches, triggers Luke's attack, which misses. Vader bull rushes Luke down the stairs.


I tried to make a rule addition that would allow a bit more back and forth. I'm afraid I may have gone overboard, with no real benefit. Here's what I came up with:


Let's start with the assumption that characters are all 1st level, with just 30 hp or so. They only ever make either basic melee or basic ranged attacks, plus bull rushes, grabs, etc. Stuff in the combat chapter of the 4e PHB, but no powers. All those attacks are standard actions. Now we add in reactive defenses.


Prepare Defense. Minor action. Choose one of the following four defensive options - parry, evade, counter, or riposte.

  • Parry. Once before the start of your next turn you can interrupt a melee attack against you. Make an attack roll with your weapon. If you roll higher than the incoming attack, the attack misses you.

    *If you are wielding a second weapon or carrying a shield, you gain a +2 bonus to your parry roll.

    **For those inclined to more realism, you can add this. If you try to parry a weapon larger than your own, you take a -2 penalty if the weapon is one size larger, or -5 if two sizes larger. You cannot parry a weapon three or more sizes larger. (A large giant’s two-handed weapon counts as 3 sizes larger than a human’s shortsword.) Thrusting weapons are parried as if one size smaller.

  • Evade. Once before the start of your next turn you can interrupt an attack against you. Make an Initiative check vs. the attacker’s Passive Insight. If you succeed, you move 5 ft. and the attack misses you if the attacker can no longer target you.

    You can evade arrows, for instance, if you duck into cover.
  • Counter. Once before the start of your next turn you can interrupt a melee attack against you. Make a melee basic attack against your attacker. If you hit, the attacker takes a -2 penalty to his attack roll. If you miss, you grant combat advantage against the attack.

    ***For those inclined to more realism, you can add this. If you try to counter attack with a weapon larger and slower than your foe’s, you take a -2 penalty if your weapon is one size larger, or -5 if two sizes larger. You cannot counter with a weapon three or more sizes larger.
  • Riposte. Once before the start of your next turn you can react to a melee attack against you. After the attack resolves, make a melee basic attack against your attacker. If your attacker missed you, you gain a +2 bonus to your attack roll.

You cannot use any of these options if you grant combat advantage to the attacker. Preparing a second defense in the same round requires a standard action, in addition to the minor action for the first defense.


Desperate Defense. Immediate Interrupt. You can parry or evade even if you didn't prepare the defense on your turn, but you end up prone afterward.


Now, let's take the Empire lightsaber duel.

Round 1, Luke and Vader see each other. If this were a brawl, Luke would just charge in, but this is honorable so he closes, ignites his lightsaber, and preps some defense. Vader ignites his lightsaber and preps a parry and riposte (which takes a standard and a minor).

Round 2, Luke starts his second turn (so his defense last round went to waste). Uncertain about his skills, he starts defensive. He preps a parry, then attacks. Vader responds with his parry, and blocks Luke's attack. Then Vader ripostes, and Luke uses his own parry (even though it's still his turn), and manages to block Vader.

On Vader's second turn, he again preps a parry-riposte.

Turn 3, Luke attacks, and Vader parries, then ripostes with a bull rush, and Luke loses his footing because he's balancing at the top of a staircase. Luke realizes his mistake, and preps a counter attack.

Vader wants Luke alive, though, so he preps a double evade.

Turn 4, Luke starts an attack, but Vader evades. Luke spends a move action to step up, then preps a defense, but it doesn't matter.

On Vader's turn, he preps a parry-riposte.

Turn 5. Luke preps a parry, and attacks (it's several sword swings, but it counts as one attack). Vader parries Luke's volley, then ripostes. Luke parries.

On Vader's turn, he preps his regular parry-riposte.

Turn 6, Luke twirls for some reason (maybe it's a feint; maybe he just doesn't realize how bad twirling is in combat), preps a parry, then attacks. Vader parries, then ripostes. Luke parries.

On Vader's turn, he actually attacks, and Luke makes a desperation evasion to duck out of range. He falls to his hands.

Turn 7. Luke stands, preps an evade, and backs away. When Vader takes his opportunity attack, Luke dodges out of the way.

Vader congratulates Luke's skills, and preps parry-riposte.

Turn 8. Luke preps a parry, then attacks. Vader parries, then makes his riposte, which Luke fumbles. He loses his weapon, and to avoid Vader's riposte, he desperately evades, and falls down the stairs.

On Vader's turn, he charges.


That's probably a little too complicated, for no real effect, right? Also, it only works if parries almost always succeed.
 


Ranger wicket,

You can fight that fight using the Codex system, including all the features you wanted like the counterattacking, changing the pace of the fight back and forth, desperation defense etc., and all at a fast pace without a lot of paperwork, no charts, and very little math.

If you like PM me with your email and I'll send you a comp copy of the Codex to evaluate and, if youu see fit, comment upon here.

G.

P.S. Incidentally, that fight was choreographed by veteran fight coordinator Bob Anderson, who was in the Darth Vader suit during the fight and trained Mark Hamill for the scenes... you can see him in the film Reclaiming the Blade talking about this and the choreography in Lord of the Rings, Princess Bride etc. Anderson was the guy who trained Eroll Flynn and was one of the few stunt or fight coordinators in Hollywood who knew Historical European Fencing.
 

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