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Another grenade question!

How do you "defend" against grenades?

I am thinking: 1st I can do the game-y version. Roll evade for half damage ("jump" to the ground, end-up prone).

I am also thinking: if your initiative is high enough and you can use your move action to get out of the area, and/or into some sort of cover then you can use your move action if evade is successful and take no damage. If you already move but did not engage anyone you can also amend it. Maybe need a perception check as well.. (spot the grenade in time)

Anyway, how do you do?

Also thinking to apply that to "fireball spells"

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Solid barriers will block shrapnel from explosives. But fireball? Unless one is in a room totally sealed off from the center of the fireball, the heat/flame will expand around openings*. Both may produce some form of shock wave (especially a concussion grenade vs fragmentation type) -- not sure how tightly the shock wave will follow around openings; there may be a shadow effect that is calm.

 

* Very old AD&D outing. Party was in "strategic retreat" from some big-bad. I had a magic user with one spell left, a fireball. I had the rest of the party go out the room and down the hallway while I stayed to set off the fireball at point-blank range. Yes, suicidal "final strike" character. Magic user somehow survived the fireball, which did take out the big-bad... my other character (the group normally ran two characters at a time in case one gets killed) who was way down the hallway outside the room... did not survive the back-blast.

 

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3 hours ago, Lloyd Dupont said:

Another grenade question!

How do you "defend" against grenades?

1. Dive behind cover. 

2. If you are already some distance away you can drop prone and hope the fragments go over your head.

3. Grab grenade and throw it away, hopefully making it someone else's problem.

4. Find something to cover the grenade with, such as a helmet or a ally you're not that fond of.

 

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4 hours ago, Lloyd Dupont said:

How do you "defend" against grenades?

Catch and Throw, Kick Away, Dodge, Smother with Body.

 

 

41 minutes ago, Atgxtg said:

Dive behind cover. 

2. If you are already some distance away you can drop prone and hope the fragments go over your head.

3. Grab grenade and throw it away, hopefully making it someone else's problem.

4. Find something to cover the grenade with, such as a helmet or a ally you're not that fond of.

 

Hah! The same as mine, just 41 minutes earlier.

Edited by soltakss
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5 hours ago, Lloyd Dupont said:

How do you "defend" against grenades?

 

Cricket bats!

 

1 hour ago, Atgxtg said:

4. Find something to cover the grenade with, such as a helmet or a ally you're not that fond of.

 

5. Cover it with the body of a foe!

ETA live or dead!

Edited by Bill the barbarian
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I was looking for game mechanic guys! :)
I guess it means you agree with the game mechanic I went with?! 😮 

I guess kickback is another option, if your initiative is before the grenade initiative...

On that topic, wondering if the grenade should go same round (initiative tricky because it need be less than the thrower, obviously.. but how much less?) or at the beginning of next round!

 

5 hours ago, Baron Wulfraed said:

Magic user somehow survived the fireball, which did take out the big-bad... my other character (the group normally ran two characters at a time in case one gets killed) who was way down the hallway outside the room... did not survive the back-blast.

How does that work?
Damage is on a 3 meter radius, is it not?! 😮 

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I'm going to explain to you what I know regarding today's grenades.  Futuristic grenades may or may not follow these laws of physics.  FIRST, grenades use have two methods of causing injury.  The first is the OVER PRESSURE BLAST EFFECT.  This is the actual force of the explosive in the device (grenade, rocket, artillery or mortar shell, or mine).  Some devices like grenades will have a smaller "explosive filler" to propel the primary method of injury... fragments or shrapnel.  Other devices use their "explosive filler" as their primary wounding mechanism.  Artillery shells fall into this category.    Over Pressure Blast kills by essentially crushing or smashing the body.  It is subject to the INVERSE SQUARE LAW.  This means that as a rule of thumb, the blast damage halves every time the range doubles.  This is why a modern US Frag grenade as a lethal or kill radius of 5m but an effective "fragmentation range" of 12m to 15m (depending on which generation of frag grenade you are dealing with).  The kill radius is including the blast damage but the frag radius is the range at which there is a 50-50 chance of fragmentation hitting you.  Note that the US Frag grenade has a maximum fragmentation range of 24 meters.  This means that you can be hit by a fragment this far away from where the grenade landed. 

        Over Pressure Blast Effect is like water or gas.  It will fill EVERY SQUARE INCH of the area of effect and there is no way to hide from it.  Thankfully, due to the INVERSE SQUARE LAW, it drops off VERY QUICKLY.  The majority of explosives will have a BLAST EFFECT that affects EVERY location on the target's body.   The typical Frag grenade would do 2D6 at the first range band and 1D6 at the second range band while dropping off completely at the third range band.  Some explosives, mostly Hyperbaric munitions (using highly reactive dust like aluminum and lithium) and Thermobaric munitions (using vaporized fuel) can destroy the very air and turn human beings in their blast radius into mush or liquid (known as an OVER PRESSURE EFFECT).   These explosives are sometimes called "Implosion Bombs"  and are best used inside of structures to "implode" those structures.  For those interested in the physics of the blast effect, a commercial stick of dynamite generates one Megajoule of energy. 

  FRAGMENTATION EFFECTS can carry for much greater distances than BLAST EFFECTS can.  They can reach up to FIVE TIMES the distance a blast will reach.  It uses its momentum to cause punctures and lacerations to the people in the Fragmentation Range.  The US Frag grenade has a 5m "Kill radius"  but I think the enhanced Twilight2000 deals with this in a better way.  In Twilight's enhanced system (found in Challenge Magazine), the base range for BOTH frag and blast is 6m.  The second range band is 12m.  The third range band is 18m and the final range band is 24m.  The blast is only apparent in the first two range bands and frag chances drop off for each range band you go out.  This makes calculation of damage line up with the range band the target is in.

Other Explosive Effects:

There are a couple of additional explosive types that must be addressed.  The HIGH EXPLOSIVE DUAL PURPOSE (HEDP) and the HIGH EXPLOSIVE ANTI-TANK (HEAT) warheads.  

HIGH EXPLOSIVE DUAL PURPOSE (HEDP):  A common round for both artillery and grenade launchers, it splits the difference between a true "armor piercing" round and an "anti-personnel" round.  It uses a casing to direct the majority of blast effect towards the target.  It would have the full blast and frag effects for whatever it hit, BUT... the blast effects and fragmentation for anyone near the sides of where the round impacted would be halved.  In Twilight2000, these rounds tend to have a smaller blast radius and lower chance of catching fragmentation.  The grenade above, might have a 4m blast instead of 6m IF it were an HEDP round.  

HIGH EXPLOSIVE ANTI-TANK (HEAT):  This round is designed to punch through armor.  It uses a hardened nose cone shaped like a funnel to compress and direct the blast into the target.  This causes the blast to actually form a jet of molten PLASMA that will cut through the target's armor like a blow torch.  MOST of the round's energy will be directed through this hole.  Thus, a HEAT round the size of the Frag blast pattern above will have a blast pattern 6m long by 2m wide in Twilight2000.  In addition, the chance of catching fragmentation when standing to the side of the impact is 25% to 35% due to the shaped charge directing the blast at the target.       

 

AVOIDING DAMAGE:

     There is NO WAY to avoid blast damage.  It flows like water or gas and fills every nook and cranny of the space.  In fact, if the blast is BIGGER than the space it occurs in, the blast damage will be magnified. 

      Fragmentation is easier to avoid.  It is projected up and out and just going prone will reduce your chances of being hit.  Soft objects CAN slow or absorb fragmentation.  Things like interior walls, furniture, or brush CAN reduce your chance of getting hit.  This is why the US Army uses 4-ply plywood in its Forward Operating Bases.  It has proven to stop fragmentation from mortars and hand grenades as long as you're not in their "kill zone."  Hard objects like K-Rails, sandbags, and engine blocks will stop fragmentation completely.    

 

                 

Edited by olskool
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Thanks for the detailed physics explanation :)

I am particularly interested n game mechanic ideas though....
Explosives are listed page 267 of the BGB
You can see "Grenade, Shrapnel" 4D6/4 meters, or "Grenade, Plasma" 6D6/1 meters.

It looks like, I succeed at my roll skill, you dead. I have a problem doing that to my players, I feel bad about it. I like it better when they can attempt something.... (even though, I guess futuristic grenade should really kill you hey?!)

So, in game mechanic term what can they achieve?
According to the BGB you can "evade area damage" for half damage... here I am a little conflicted, player tells me "the monsters are in this square empty room, how come they can evade"? (though they don't really complain about their own evade roll, those sneaky bastards! :P )  so I am not sure if I should give in.. and requires some tactical action (i.e. use of movement and cover)
 

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30 minutes ago, Lloyd Dupont said:

I was looking for game mechanic guys! :)
I guess it means you agree with the game mechanic I went with?! 😮 

I guess kickback is another option, if your initiative is before the grenade initiative...

On that topic, wondering if the grenade should go same round (initiative tricky because it need be less than the thrower, obviously.. but how much less?) or at the beginning of next round!

 

How does that work?
Damage is on a 3 meter radius, is it not?! 😮 

I would use the system Twilight2000 used.   You give each grenade a base range in meters.  You then allow for 3 more "Range Bands" of an equal length in meters.  The blast is full in the 1st range band.  It is halved in the next range band and quartered in the 3rd range band.  Frag hits are rolled for with 2D10 hits possible in the kill radius (1st range band).  There would be 2D6 frag hits in the second range band.  You would roll 2D4 for frag hits in the 3rd range band and finally 1D4 for frag hits in the final range band (I use 4 range bands in my games for uniformity across game platforms, you may need to change this).   Each Frag hit does 1D4 damage and the locations are rolled randomly.     

IF the target goes prone, divide the frag hits in half rounding down.  Treat 0 as a 0.

If the target is protected by a soft object, halve the frag hits as above.  IF the target is also prone, treat them as one range band farther away before you roll and half the frag hits. 

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7 minutes ago, Lloyd Dupont said:

Thanks for the detailed physics explanation :)

I am particularly interested n game mechanic ideas though....
Explosives are listed page 267 of the BGB
You can see "Grenade, Shrapnel" 4D6/4 meters, or "Grenade, Plasma" 6D6/1 meters.

It looks like, I succeed at my roll skill, you dead. I have a problem doing that to my players, I feel bad about it. I like it better when they can attempt something.... (even though, I guess futuristic grenade should really kill you hey?!)

So, in game mechanic term what can they achieve?
According to the BGB you can "evade area damage" for half damage... here I am a little conflicted, player tells me "the monsters are in this square empty room, how come they can evade"? (though they don't really complain about their own evade roll, those sneaky bastards! :P )  so I am not sure if I should give in.. and requires some tactical action (i.e. use of movement and cover)
 

The problem is that an explosion is a DUPLEX EFFECT.  You have the shock wave (which cannot be avoided) then you have the fragmentation and debris launched from the point of detonation.  They really are TWO SEPARATE EFFECTS and must be dealt with differently. 

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BTW I use general HP...

Localised HP seems fine in medieval setting and "low damage" weapons (in fact it increases survival since you can take chip damage on each location for more that overall HP! 😮 ) , but as soon as you go modern or futuristic weapon or high damage spell... It doesn't work so well.. i.e. it's much less fun to have instakill whoever lose initiative every fight....

Edited by Lloyd Dupont
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8 hours ago, Lloyd Dupont said:

I was looking for game mechanic guys! :)

Catch and Throw: Make a DEXx5% roll to catch it and a Throw roll to throw it away

Kick Away: Make a Kick roll to kick it away

Dodge: Just a normal Dodge, or maybe a jump to get really clear

Smother with Body: The body absorbs all the impact, but takes full damage

Cricket bats: Make a Mace or Maul attack roll

Teleport/Flight: Cast your spell on it and move it out of harm's way

Depending on the type of grenade, simply casting a spell such as Extinguish might be enough to kill the fuse.

8 hours ago, Lloyd Dupont said:

I guess kickback is another option, if your initiative is before the grenade initiative...

On that topic, wondering if the grenade should go same round (initiative tricky because it need be less than the thrower, obviously.. but how much less?) or at the beginning of next round!

Using RQ-style Strike Ranks, not DEX Ranks, as I am not sure how they work with DEX Ranks.

There are three things to think of here, when the fuse was started, how long the fuse lasts, what the SR of the Throw is.

I normally measure fuse lengths in SRs, as it makes it easier. 

So, someone with DEX SR 2 uses a 10 SR fuse, setting it off at SR2 and throwing it at SR 5, it would explode at SR 2 next round. Assuming it lands the next SR, the targets would have between SR6 and SR10 that round to react, or to do something on SR1 next round.

Clever NPCs would wait for the end of the round to throw the grenade, as it means it explodes as it lands.

However, it might be worthwhile having a fuse time of 1D6+6 or something similar, to make it a bit more random.

 

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8 hours ago, Lloyd Dupont said:

I am particularly interested n game mechanic ideas though....
Explosives are listed page 267 of the BGB
You can see "Grenade, Shrapnel" 4D6/4 meters, or "Grenade, Plasma" 6D6/1 meters.

It looks like, I succeed at my roll skill, you dead. I have a problem doing that to my players, I feel bad about it. I like it better when they can attempt something.... (even though, I guess futuristic grenade should really kill you hey?!)

You use the Throw skill to drop the grenade roughly where you want. A Special or Critical gets it closer to the spot you were aiming at. This makes it a bit more random.

As a GM, you allow PCs to see the grenade and react, even when perhaps they shouldn't be able to react. Maybe you give them a chance to see the grenade before it is thrown or allow them to stop it being thrown.

If they can react, allow them to move away or hide behind something. Sure, the blast effect might not get stopped but it might be reduced slightly.

Even putting a waste bin over the grenade might reduce the impact by muffling it or constraining it. Some people carry blast capes that they can throw over a grenade to contain the blast.

In my opinion, GMs can say "The NPC throws a grenade at you, it explodes and you all take 4D6 damage", or "The NPC throws a grenade at you, what do you do?". I know which I would prefer to say.

 

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41 minutes ago, soltakss said:

Clever NPCs would wait for the end of the round to throw the grenade, as it means it explodes as it lands.

However, it might be worthwhile having a fuse time of 1D6+6 or something similar, to make it a bit more random.

You gave me an idea....
In fact a few ideas! :)

But the one I am particularly quoting here....
Throw skill will give the grenade 10SR less than the thrower... (easy to dodge if you see it coming), but the grenade skill will work just the same but with reduced SR cost.. maybe 5, or D4 in case of crit....

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6 hours ago, soltakss said:

So, someone with DEX SR 2 uses a 10 SR fuse, setting it off at SR2 and throwing it at SR 5, it would explode at SR 2 next round. Assuming it lands the next SR, the targets would have between SR6 and SR10 that round to react, or to do something on SR1 next round.

 

Granted, I've not studied modern grenade usage, but... The common (as seen in war movies) grenade fuse is started by the handle being released -- and said release occurs when the grenade has been thrown, and the handle flips off.

Your above description has the user holding the body of the grenade, deliberately letting the handle flip into the air, and then counting down for a throw. Per Wikipedia https://en.wikipedia.org/wiki/Grenade

Quote

This technique is inherently dangerous, due to shorter delay (meaning a closer explosion), greater complexity (must make sure to throw after waiting), and increased variability (fuzes vary from grenade to grenade), and thus is discouraged in the U.S. Marine Corps, and banned in training

 

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18 hours ago, Lloyd Dupont said:

I was looking for game mechanic guys! :)

Okay, in that case:

1. Dive behind cover. 

  • Can be dome with a Jump roll (or possibly a Dodge roll) with the protection determined by the cover.

2. If you are already some distance away you can drop prone and hope the fragments go over your head.

  • I'd probably use a Luck roll here to avoid getting hit, and probably adjust the difficulty by range as the further out you are the less likely would would be to get hit.

3. Grab grenade and throw it away, hopefully making it someone else's problem.

  • You might want to use a DEX roll here to get rid of it before it goes" boom" or just a hard Throw roll. 

4. Find something to cover the grenade with, such as a helmet or a ally you're not that fond of.

  • Get protection based upon what you put onto of it. I'd suggest double damage to whatever gets sacrificed upon the grenade, but probably no damage to anyone else.
18 hours ago, Lloyd Dupont said:

I guess kickback is another option, if your initiative is before the grenade initiative...

 

I wouldn't tie things to the initiative count. Realistically in a grenade lands at you feet right before/during/after you take a shot, you still have a second or two to react. Otherwise you will wind up with player playing all sorts of timing tricks to get the enemy committed to action so that they can't do anything about the grenade. Instead I'd look at it more like a dodge or parry, namely as a reaction to an attack. I'd make it a hard roll, since you only have a couple of seconds to act, but otherwise not worry about intiative counts.

Besides, a combat round is 12 seconds, while a typical grenade will explode in only 4 seconds. 

18 hours ago, Lloyd Dupont said:

On that topic, wondering if the grenade should go same round (initiative tricky because it need be less than the thrower, obviously.. but how much less?) or at the beginning of next round!

Well by RAW it goes off off like any other attack- it explosed on the same Strike/DEX rank as it was thrown. It doesn't just sit there for a full round. THat's why I think it's best to make any sort of reaction to the greande a free reaction similar to a dodge, or parry. 

 

18 hours ago, Lloyd Dupont said:

 

How does that work?
Damage is on a 3 meter radius, is it not?! 😮 

It depends upon what version of BRP you are using, but I believe the damage droops off a die every so many meters. BRP Gold Book Grenades to 4d6/4m, and drops off 1 die per additional meter. That's actually much kinder than real life, where the drop off would be more along the lines of 1 die per 4m.

BTW, the gold book does have rules for diving prone (Dodge to avoid damage, or DEXx5% for half damage).

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Thanks for your excellent reply! :) 

Otherwise...

4 hours ago, Atgxtg said:

BTW, the gold book does have rules for diving prone (Dodge to avoid damage, or DEXx5% for half damage).

Yeah... While I never questioned D&D and its save for half mechanic...

In BRP if feels somewhat uncertain about this mechanic... so I wanted a (this!) thread to elaborate on that :) 

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7 minutes ago, Lloyd Dupont said:

Thanks for your excellent reply! :) 

Otherwise...

Yeah... While I never questioned D&D and its save for half mechanic...

In BRP if feels somewhat uncertain about this mechanic... so I wanted a (this!) thread to elaborate on that :) 

Well, if it were up to me, I'd go with Dodge or a difficult (half) Agility roll.But then there are a few things I'd houserule if I were running a modern BRP game anyway. I'm not all that thrilled with how the game handles grenades to begin with, fragmentation grenades in particular. With those grenades it less about the explosion and more about the fragments. Rather than doing  4d6, I'd probably have then do 1d6 hits for 1d6 each or some such. A flak vest is quite useful against grenades. 

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