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vicky_molokh 11-06-2014 01:36 PM

[MA] Silent Sentry Removal
Greetings, all!

There have been no less than three threads touching upon sentry removal / backstabbing, one way or another. I'm looking forward to rounding up the loose ends.

First of all, it must be said that sentry removal is a risky activity that is sometimes easier done in a crude manner than with all the fancy techniques. E.g., under default adventuring sound conditions, a bolt-action .30 rifle fitted with the best suppressor has less than 10% chance of being heard if fired from 70 yards away, 50% chance from 10 yards (assuming Per 10 for the enemies). A shot without a silencer will be heard from far, but might not be considered anything particularly unusual if there's a low-intensity combat activity going on in the vicinity for days nonstop with occasional high-intensity ones (e.g. what the current reports about Donetsk Airport seem to be indicating).

The very act of sneaking up to someone requires significant Stealth to pull off reliably, since it takes a roughly unmodified Quick Contest to quietly sneak up on someone from behind. (There's an entry implying that doing it reaaaalll slowww can give -2 to enemy Hearing.) Sneaking through partially-seen areas will only make things worse.

Garrottes are okay at what they do, but require too much training.

Knives seem to be good-ish at causing grievous wounds, given their modest size, assuming proper attack options and targets - some combination of All-Out Attack, Telegraphic Attack, Evaluate, Mighty Blows, and a Vitals, Neck or Skull Target Location seem to be the way to at least cause a Major Wound, if not outright negatives, plus potentially a nasty bleeding that's hard to stop.

But there's also the issue of silence, and that seems to be the problem.

Silence requires some way of preventing both screams and other sources of noise. The former seems to require grappling the mouth or neck - which makes Choke Hold a good choice, with its modest -2/-3 default modifier, +5 to resist breaking free if using two hands, +3 to ST for choking and strangulation purposes, and a nasty nasty nasty MoS-based and time-based FP-damaging attacks that can be used to reliably knock out (and likely kill) the target by doing a fixed amount of damage.
The first big thing working against Choke Hold is that even an unaware target gets to use a grappling-based Parry at an extra -2 (which apparently means a total of -6 due to also not being able to see the attacker). For a skill-12 enemy, that means a Parry against (12/2)+3-6 = 3. Which doesn't seem like much at all, but in case of a Telegraphic Attack and a Feverish Defence, it can go up to 7 (about 1/6 chance).

The second big problem of Choke Hold is that the enemy still has free hands. Sure, that's at least -4 to DX for being grappled, and the Shock modifier on the following turns, assuming some damage done and no HPT. But that might still be enough to shoot randomly and repeatedly right next to the enemy camp, which . . . tends to be viewed differently.

I wonder whether it's faster to go for a Choke Hold with knife in right hand, with the left hand being the 'main' grappling one, while the right arm being merely assisting as if handless (i.e. 'crook-of-arm' applied to only one arm, while the other is fully operational), then releasing one hand after the choking started (thus relinquishing the +5 to hold on), and going for a Vitals stab (AoA or not) on the second turn of combat.

Or maybe AoA Grab-and-Stab is better?

What approaches have your character been using? What are the upsides and downsides I missed for different approaches? Which ones are better overall?

Thanks in advance!

Varyon 11-06-2014 04:01 PM

Re: Silent Sentry Removal
I think the typical method for melee sentry removal (ranged is probably more common, although I could be mistaken) is to sneak up behind and put them in a blood choke. Human beings, even those with Combat Reflexes, simply don't react as quickly as they do in GURPS. I think they also typically don't patrol with their fingers on the trigger guard of a weapon with its safety off.

Assuming the target expected an attack and/or has Combat Reflexes, they're going to start out under conditions of Partial Surprise, being Stunned and unable to act. Assuming you manage to successfully start the choke hold, a Fright Check may be appropriate - unexpectedly losing the ability to breathe is terrifying! If the target passes that and manages to shake off the stun, opting to fire his weapon to inform his buddies rather than grabbing the arm in an attempt to pull it off so he can freaking breathe should probably call for a Will check. Following that, he'll probably need to use a Ready to turn his weapon's safety off, and the GM may call for a Guns check to manage this while grappled (and the attacker should be able to Parry the attempt by shaking his victim at the wrong moment). After that, probably another Guns check is needed to get a grip on the trigger (again, attacker may be able to Parry) before he can actually fire. During all this time, the attacker is strengthening his grip (if using Technical Grappling) and/or possibly attempt to disarm him by shaking him around or whatever (he might also be attempting Strangle, Head Lock, Neck Snap, or similar). The end result is that even if the defender has ice water running through his veins, he's probably unconscious before he can sound any sort of alarm. Against a sentry who does have ice water running through his veins, it might be best to start the attack with All Out Attack (Double), grabbing his weapon/hand with one arm and his neck (in a Choke Hold) with the other. Get his weapon away from him, then switch both hands to the Choke Hold and wait till he passes out.

Crakkerjakk 11-06-2014 04:05 PM

Re: Silent Sentry Removal
We were taught to grab the mouth and saw at the neck frantically with a large knife. Helps if you can have someone else there to grab them and prevent some of their larger gear from hitting the ground too loudly.

johndallman 11-06-2014 04:18 PM

Re: Silent Sentry Removal
The plan I've been looking at for a while for a character who's likely to need it someday goes:

Sneak up, with sufficient stealth, aided by invisibility. All-out Attack (Double). Right-hand grapple to the face (-3) to hold the mouth shut; left-hand stab to the vitals (-3) with a very fine long knife, doing 1d+2, with x3 wounding. I need to buy up some skills and ST to make this practical.

In the setting (WWII), sentries are normal humans and unlikely to have armour, so one can plausibly expect to do a major wound and have good odds to put the target into negative HP.

One can't use Grab and Smash with a face grapple and a torso stab. The alternative is to grapple the face and use G&S with a stab to blood vessels in the neck. That gives 1d+4 with wounding x2.5, for slightly higher damage but the attack penalty is -8, which is a bit tough.

Edit: Most of this is based off Martial Arts: Fairbairn Close Combat Systems.

Dalillama 11-06-2014 04:54 PM

Re: Silent Sentry Removal

Originally Posted by johndallman (Post 1833834)

Edit: Most of this is based off Martial Arts: Fairbairn Close Combat Systems.

Which is definitely the book to use for this topic.

Xakaz 11-06-2014 09:44 PM

Re: [MA] Silent Sentry Removal
It worth to think which attacks may hinder your foe's ability to scream without grappling his face or neck. Stabbing his neck (not blood vessels) may damage his vocal cords. And stabbing his lungs may impede his breathing, at least muffling his screams.
Probably, best way to remove sentry without helmet - is just Telegraphic AoA (Strong) to his skull with something heavy. At least in action movies, in this case your foe will quite reliably fall unconscious without making any shouts.

fifiste 11-07-2014 03:09 AM

Re: [MA] Silent Sentry Removal
A tomahawk etc. to bare skull should be pretty good indeed -10HT check to avoid knockdown and if it failed by -5 insant uncounsciousness.

vicky_molokh 11-07-2014 04:59 AM

Re: [MA] Silent Sentry Removal

Originally Posted by fifiste (Post 1834046)
A tomahawk etc. to bare skull should be pretty good indeed -10HT check to avoid knockdown and if it failed by -5 insant uncounsciousness.

Let's see . . . Tomahawk does sw+1. For ST10, that's 1d+1. With AoA (Strong) or Mighty Blow, that's 1d+3, which is the bare minimum for guaranteeing no less than 4 base damage that is required to reliably penetrate the skull (no helmet) and cause a Major Wound against normal opponent (24 = 8), resulting in an effective HT-5 roll to stay conscious (HT-10 to resist Stun). That's about a 1/20 chance (assuming HT10) that the guard will not be knocked out immediately, and it's unclear whether the guard will scream from the stunning. With HT10-12 and Fit/Very Fit, the chance of a mere stun can rise up to 1/3 (plausible worst case scenario).

The attack against Skull is, IIRC, at a mere -5 from the back. Taking Telegraphic Attack, that's -1. No, AoA (Determined) isn't safe to pick, because it will not allow using AoA (Strong)'s or Mighty Blows' damage bonus. IOW, if one *does* pick AoA (Determined), it's a tradeoff between hitting the skull and doing enough damage to make sure there's no follow-up noise other than the two thuds.

Erling 11-07-2014 05:08 AM

Re: [MA] Silent Sentry Removal

Originally Posted by vicky_molokh (Post 1834068)
and cause a Major Wound against normal opponent (24 = 8), resulting in an effective HT-5 roll to stay conscious

I must have missed something. Why HT-5 to stay conscious?

UPD: Oh, it must be about MoF 5 causing unconsciousness... Now I get it.

Tomsdad 11-07-2014 05:24 AM

Re: [MA] Silent Sentry Removal
The problem is the GURPS combat system is written around weather or not the target screams as these various thing happen to them, leaving it up to the GM to decide (nothing wrong with that)

As GM I'd happily argue that a good face grapple (maybe 2+ CP) will cover the mouth and muffle shouts if the grappling is saying that what they are intending.

A choke hold I'd be less sure of (again maybe at a certain level of success)

Hits to the skull again I'd hesitate to say even an instant kill would guarantee no shout.

I think surprise is a major factor here, but again doesn't explicitly say weather or not a shout is part of "doing nothing".

The thing is though the silent kill is a bit of Hollywood convention, I think 'quite' was the general goal not silence.

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