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Old 09-13-2020, 07:31 PM   #11
Doctor of GURPS Ballistics
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Join Date: Sep 2004
Location: Burnsville, MN
Default Re: Technical Grappling: Grabbing Parry clarification

Originally Posted by Varyon View Post
The additional roll will often make the chance of success higher, because it puts the additional penalties on the second roll, not the first. Consider a character with skill 12 in a grappling skill, who hasn't trained up Grabbing Parry. With the two-roll version, to grab an arm that's punching at him, he needs to roll against 7 (his Parry is 9, -2 for Grabbing Parry) then 11 (skill 12, -1 to grapple an arm). His chance of pulling it off is (0.162*0.625)=10.125%. With the one-roll version, he needs a single success against 6 (Parry 9, -2 to Grabbing Parry, -1 for arm, as stated in the Technique), which is a 9.25% chance. If he had bought up the Technique to full, the two-roll version would be a roll against 9 then 11 for (0.375*0.625)=23.4%, while the one-roll version would be a single roll against 8, with a 25.92% chance of success. That's slightly higher, but if you work out probabilities for characters with skill above 12 (that is, the majority of characters who are likely to actually try Grabbing Parry), two-roll consistently gives a better result than one-roll. This also has the advantage of matching with the way Aggressive Parry and Jam work.

The roll for attempting to damage the target when using Aggressive Parry/Jam is unopposed, so if we have Grabbing Parry work like that, we don't need to worry about a QC. Indeed, as it stands, if we just add in this extra roll to Grabbing Parry, it behaves almost exactly as one would expect from an Aggressive Parry that replaces the strike with a grapple (the modifiers to hit are halved, as normal for hit locations when grappling, the only difference is that the damage penalty is in the form of using 0.5xST rather than taking a -3 to damage).
All of this is well argued; certainly it has the "use what's there" "Rules for Grappling Rules" down.
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Old 09-14-2020, 03:12 PM   #12
Join Date: Aug 2018
Default Re: Technical Grappling: Grabbing Parry clarification

Originally Posted by Varyon View Post
To be clear, Aggressive Parry does not state that you make an attack roll, or anything of the like. Rather, it states that, on a successful Aggressive Parry, you roll against skill (with modifiers as described) and, on a success, inflict damage. That's hardly ambiguous, I think.
"roll against the underlying skill to strike the attacking body part or weapon" with identical penalties for hit locations (-2 limb -4 extremity) is about as close to 'attack roll' you can get for Aggressive Parry (and Jam) without saying it.

RAW since you're not TECHNICALLY doing an attack/technique, having Targeted Attack bought up wouldn't reduce that penalty... but it's a pretty reasonable thing to ask for.

RAW since it's not technically an attack you might argue the -2/-4 penalty to attack from lower postures (which can be mitigated with a technique which also mitigates defence penalties, GRound Combat or someting I think) would not apply, but that also seems reasonable to house-rule.
MA99 options too, if you use Aggressive Parry against a bite or headbutt then the -7/-6 to hit the skull/jaw should probably be reduced to -6/-5 of a kneeling or sitting man...
...and if you are kneeling then you should be only -1/-2/-3 to "Aggressive Parry punch" the leg/groin/foot of an attacker instead of the usual -2/-3/-4
I guess the important distinction is that since it's not a 'normal attack' you wouldn't have options like Deceptive Attack (kinda pointless if they can't defend to stop the damage, but maybe some cosmic defenses could?) or Telegraphic Attack (too much of an 'I win' with no tradeoffs if defense is not even allowed)

...or certain combat options (ie the normal ability to use "Tip Slash" to convert impale-only attacks to cutting damage, or 'flatting' to convert cutting to crushing, or 'pummeling' to do crushing with ANY weapon). IE you can't "flat parry" using an axe (all parries must do cutting damage), or choose to "pummel parry" or "tip-slash parry" using a spear, all parries using spear skill must do impaling damage.

There is of course some unique differences... if we view AP as a 'punch' then...
-2 to punch a foot or leg w/ boxing (not brawl/karate)
-6 to -8 to punch weapons
-3 to punch swung weapons for box/brawl (not karate)

The obvious pattern here is that penalties to parry appear to apply as penalties on the hit too, so boxing isn't just bad at parrying kicks, it's bad on successful parries damaging the kicks.

Brawling isn't just bad at parrying swung weapons, it's bad at damaging those swung weapons even when it does successfully stop their damage.

The "basic -3" to hit weapons (independent of B400 size penalties) I can only explain by MA124 Harsh Realism - Parrying Weapons being assumed in effect and floating that over to the strike roll.

- - -

Jam on MA75 even says "the usual -2 for kicking" to fuel the idea you're essentially making a 'free attack'. I would posit it's a realistic houserule to avoid that -2 for those who bought up the Kicking Technique, for example (or per MA99 if you are Lying Face Up).
similarly, applying the -2 kneel/sit or -4 lying penalty to attacks to this "skill roll" for Jam or AP probaly makes sense to do, though RAW you would not. Of course avoidable by Ground Combat technique
Jam has uniquely different hit location penalties though:
+0 to hit leg
-2 to hit arm/foot
-4 to hit hand.
This is basically the usual (-2 limb -4 extrem) with +2 to hit lower body though, or "removing -2 in penalties"

My guess is this is channeling MA99's +1 to kick legs/feet of standing men (if you are also standing) though I'm not sure why they doubled it (normally you need Crawling/Lying to remove -2)

Originally Posted by Varyon View Post
Endless, no, but with good Parry scores (and using a one-handed skill, where you can keep alternating which hand you use to Parry to slow the accumulation), it can certainly go on long enough to get rather annoying... and potentially silly.
A simple way around this: if allowing defenses against the attacks generated by things like Jam / Aggressive Parry / Hand Catch (and modified Grabbing Parry) make "no contact-parry" the ONLY way to parry the attack roll.

No-contact parries can't be aggressive so the chain ends there: it represents a last-minute "pulling the punch" when you realize you're going to get counterattacked.

In that case you not only avoid the counterattack but also the 'contact' a normal successful parry would result in.

This "last minute option to avoid contact" could be allowed for attacks in general if something could change the attacker's mind. Like for example a cute kitten doing a sacrificial dodge in front of the evil wizard: give the attacker a last-minute chance to avoid that kitten as he realizes it's becoming a "human shield".

That's not just for good guys: if that "sacrificial kitten" has Burning Attack 10 (Aura) then you're going to want to avoid hitting it anyway to avoid incinerating your hand.

Another example would be "near miss" issues: you wanted to hit the Jaw but missed by 1 and are going to hit the Torso-Only Reflection DR, no-contact parry to pull the punch so you don't hit the torso.

Or: "I only punched expecting he would parry" (probably telegraphic) so if you notice a failed parry roll, a "no-contact parry" could be "wow he's not trying to stop this, I don't actually want to hit him!" last-min stoppage.

Originally Posted by Varyon View Post
I wasn't saying the penalty for Grabbing Parry was worse than the penalty Aggressive Parry, but rather that it was calculated differently.
There are some ST's for which 0.5xST is worse than a flat -1 damage and -1/die or -2 (whichever is worse), there are some where it's better, and there are some where it's equal.
For example, a character with ST 10 is at 1d-4 at ST/2 but 1d-5 at -3, a character with ST 20 is at 1d-2 at ST/2 but 2d-4 (which can be simplified to 1d or 1d-1, depending on how you round) at -3, and a character with ST 15 is at 1d-3 either way.
The distinction to me is that -damage is ALWAYS a penalty while 0.5xST isn't a penalty at all for someone who already uses 1-handed grabs and doesn't have the beyond-DX combat training needed to get a trained ST bonus.

Either a reduction to 'damage' (control points) or to ST (used to calculate it) would make it more of a consistent drawback.

I'd rather include trained ST too because otherwise it weirdly makes grabbing parry a greater drawback to those with high skill (lose a bonus) than those with low skill (lose no bonus).

Also one reason I like the idea of rolling a separate to-hit is then you can compare a full skill to DX instead of comparing skill/2-1 to DX. Unless we had some rule where trained ST for defense techniques are compared to half DX instead, so that high DX isn't actually a penalty for calculating trained ST for techs (the gap between 0.5xDX and 1.0xDX is bigger)
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grabbing parry, grappling, rapid retraction, technical grappling

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