Something odd about the Bonesabres

5068 Views 76 Replies 19 Participants Last post by ChaosRedCorsairLord, Jul 18, 2010

BananaKing

Discussion Starter · Jul 14, 2010

Thus not familiar, the Tyranid Special character named the Swarmlord has weapons that if you pass an invulnerable save made against inflicted wounds by the swarmlord, you must reroll them.

So I was looking at the bonesabre rule, I noticed that it makes no mention of you having to reroll only once. I just checked the official GW Tyranid FAQ and they make no mention of it either. Now I believe you'd only have to reroll a passed save once since I don't think I've ever come across an instance where you had to keep rerolling until you fail.

However, I'm wondering that since there is no official ruling that states that the bonesabre's wounds only force one reroll, could you argue that your opponent must keep rerolling his Inv until he receives a wound? Or is there a rule in the BGB that I'm overlooking that supersedes this?

Just a thought, what do you all think?

41 - 60 of 77 Posts

ChaosRedCorsairLord

· #41 · Jul 16, 2010

Draenus said:
Well maybe i forgot to mention i play the just re-roll what ur meant to way.I see no point in cheating at toy soldiers lol.

Then there's absolutely no point in rerolling.

Does everyone know how to mathhammer rerolls? For everyone's benefit I will run through rerolls (both the good and bad type).

Pink bits are the important parts.

lets say it's a 5+AS:

So the chance of passing a 5+AS is: (2/6) = 2/6 or 12/36 (Pretty fucking obvious stuff)
So if you have 36 models that need to take an AS at 5+ you would expect roughly 12 of them to survive (poor guardsmen).

The chance of passing a 5+AS with a reroll if they fail the test is: (2/6) + (4/6)*(2/6) = 20/36
So if you have 36 models that need to take an AS at 5+ with a reroll if they fail the test you would expect about 20 of them to survive.

The chance of passing a 5+AS with a reroll if they pass the test is: (2/6) - (4/6)*(2/6) = 4/36
So if you have 36 models that need to take an AS at 5+ with a reroll if they pass the test you would expect about 4 of them to survive.

So what is the chance of surviving a 5+ AS if you reroll failed and successful ASs?
Prob(surviving) = (2/6) + (4/6)(2/6) - (4/6)(2/6)
= (12/36) + (8/36) - (8/36)
= 12/36
So if you have 36 models that need to take an AS at 5+ you would expect roughly 12 of them to survive. (Déjà vu anyone?)
Which is exactly the same as 5+!!!

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lokis222

· #42 · Jul 16, 2010

forkbanger said:
But you're just as likely to roll another four ones.

Math failure. :laugh:

forkbanger

· #43 · Jul 16, 2010

I posted this a couple of pages back-

Forkbanger said:
You would reroll every dice, and the results of the second roll are completely independent of the first. There is no point at all in rerolling everything, it makes absolutely no difference.

I mean, you could-
Roll 10 4++ saves.
5/10 pass. 5/10 fail.
Swarmlord forces the 5 passes to reroll.
Fortune forces the 5 failures to reroll.
Reroll all 10 4++ saves.
5/10 pass. 5/10 fail.

Or simply-
Acknowledge everything must be rerolled. Don't bother, as it makes no difference at all.
Roll 10 4++ saves.

And the response was that

lokis222 said:
A swarmlord only gets 4 attacks, of which only 2 will wound and those saves should be re-rolled. Unless, as someone mentioned, there is an FAQ stating otherwise. To do otherwise is a house rule.

Your useful, well-explained example is equally useless to him because the Swarmlord cannot inflict 36 wounds on a unit. Good effort that I hope some others in the thread will appreciate and understand, though.

lokis222

· #44 · Jul 16, 2010 (Edited)

ChaosRedCorsairLord said:
Then there's absolutely no point in rerolling.

Does everyone know how to mathhammer rerolls? For everyone's benefit I will run through rerolls (both the good and bad type).

Pink bits are the important parts.

lets say it's a 5+AS:

So the chance of passing a 5+AS is: (2/6) = 2/6 or 12/36 (Pretty fucking obvious stuff)
So if you have 36 models that need to take an AS at 5+ you would expect roughly 12 of them to survive (poor guardsmen).

The chance of passing a 5+AS with a reroll if they fail the test is: (2/6) + (4/6)*(2/6) = 20/36
So if you have 36 models that need to take an AS at 5+ with a reroll if they fail the test you would expect about 20 of them to survive.

The chance of passing a 5+AS with a reroll if they pass the test is: (2/6) - (4/6)*(2/6) = 4/36
So if you have 36 models that need to take an AS at 5+ with a reroll if they pass the test you would expect about 4 of them to survive.

So what is the chance of surviving a 5+ AS if you reroll failed and successful ASs?
Prob(surviving) = (2/6) + (4/6)(2/6) - (4/6)(2/6)
= (12/36) + (8/36) - (8/36)
= 12/36
So if you have 36 models that need to take an AS at 5+ you would expect roughly 12 of them to survive. (Déjà vu anyone?)
Which is exactly the same as 5+!!!

Ah, almost significant sample sizes. Yeah, they will eventually average out. Still, even at that number, you don't have enough dice for that to work consistently. Not enough samples. Furthermore, with two dice, you are looking at a distributive curve that won't be as evenly distributed as the above.

However, if you want to house rule the re-roll out, you are more than welcome to.

forkbanger

· #45 · Jul 16, 2010

lokis222 said:
Math failure. :laugh:

The odds of rolling four ones are the same in both rolls. :toot:

lokis222

· #46 · Jul 16, 2010

forkbanger said:
The odds of rolling four ones are the same in both rolls. :toot:

No, the odds of rolling a 1 on a dice is always the same. The odds of rolling a 1 twice in a row is the probability of rolling a 1 multiplied by the probability of rolling another 1.

Like mentioned. Math Fail.

Aramoro

· #47 · Jul 16, 2010

lokis222 said:
Math failure. :laugh:

No, Maths Success!.

I roll a dice and it's a 1, what's my chance of rolling a 1 the next time? 1 in 6 as the second roll is not dependant on the first.

I roll 2 dice and they're both 1, what's my chance or rolling 2 dice and them both being 1? The same, 1 in 36 as the second roll is not dependant on the first.

And so on.

What you're confusing is the probability of rolling 4 1's and then rolling 4 1's again so in effect rolling 8 1's. Rolling 8 1's is very unlikely, but that does not change the probability of rolling 4 dice and them all being 1.

I think it's time you admitted you were wrong.

Aramoro

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forkbanger

· #48 · Jul 16, 2010

Odds of rolling four ones-
1/6 x 1/6 x 1/6 x 1/6.

Odds of rolling four ones again-
1/6 x 1/6 x 1/6 x 1/6.

Both rolls carry the same probability, and are equally likely.

don_mondo

· #49 · Jul 16, 2010

And all this math and probability stuff is irrelevant. The rule is to reroll the affected dice, so you reroll the affected dice.

Dave T Hobbit

· #50 · Jul 16, 2010

lokis222 said:
No, the odds of rolling a 1 on a dice is always the same. The odds of rolling a 1 twice in a row is the probability of rolling a 1 multiplied by the probability of rolling another 1.

Like mentioned. Math Fail.

He is right; once you say probability of {event B} given {event A} you are in conditional probabilities.

The odds of rolling 4 ones on the re-roll are the same as the odds of rolling of 4 ones the first time; the odds of one following the other are the product, i.e. P1 * P2.

Applied to the original question P1 (the odds of rolling either a success or a failure) is 4/4, i.e. 1, so the product is 1 * P2, so there is no difference in rolling and re-rolling, or just rolling once.

forkbanger

· #51 · Jul 16, 2010

Since we're at the point where loki is catastrophically wrong but won't admit it (again), I'm going back to the OP.

BananaKing said:
So I was looking at the bonesabre rule, I noticed that it makes no mention of you having to reroll only once. I just checked the official GW Tyranid FAQ and they make no mention of it either.

BRB, p2 - Re-Rolls and Roll-Offs. You can't reroll a dice more than once. Since it's there, there's no need to mention it int he Tyranid codex or FAQ.

BananaKing said:
Now I believe you'd only have to reroll a passed save once since I don't think I've ever come across an instance where you had to keep rerolling until you fail.

Bang on. Each dice roll can be affected by a single reroll, whether caused by your own effect or an opponent.

BananaKing said:
However, I'm wondering that since there is no official ruling that states that the bonesabre's wounds only force one reroll, could you argue that your opponent must keep rerolling his Inv until he receives a wound? Or is there a rule in the BGB that I'm overlooking that supersedes this?

Again, the boxout on p2.

It's kind of :crazy: and :wacko: for the rest of the thread.

Aramoro

· #52 · Jul 16, 2010

He is right; once you say probability of {event B} given {event A} you are in conditional probabilities.

The odds of rolling 4 ones on the re-roll are the same as the odds of rolling of 4 ones the first time; the odds of one following the other are the product, i.e. P1 * P2.

Applied to the original question P1 (the odds of rolling either a success or a failure) is 4/4, i.e. 1, so the product is 1 * P2, so there is no difference in rolling and re-rolling, or just rolling once.

The conditional probability would matter if we care about previous results, but we don't. If the event we were looking for was roll 4 1's and then roll another 4 1's then you can combine the probability of rolling 4 1's together to give you the probability of that event.

But in this case we don't care what the previous result was, only what this result is. Rolling 4 dice will always have the same probability of rolling 4 1's no matter how many times you've done it previously. So if I roll 4 1's and then have to re-roll them all I have not decreased my chances of rolling another 4 1's. The probability of the whole event however is different.

Aramoro

ChaosRedCorsairLord

· #53 · Jul 16, 2010 (Edited)

Dave T Hobbit said:
He is right; once you say probability of {event B} given {event A} you are in conditional probabilities.

The odds of rolling 4 ones on the re-roll are the same as the odds of rolling of 4 ones the first time; the odds of one following the other are the product, i.e. P1 * P2.

Applied to the original question P1 (the odds of rolling either a success or a failure) is 4/4, i.e. 1, so the product is 1 * P2, so there is no difference in rolling and re-rolling, or just rolling once.

And hence, because there is absolutely no reason to reroll and it opens up the possibility of cheating/abuse we should not bother with the reroll.

forkbanger said:
Since we're at the point where loki is catastrophically wrong but won't admit it (again), I'm going back to the OP.

Agreed.

don_mondo

· #54 · Jul 16, 2010

ChaosRedCorsairLord said:
And hence, because there is absolutely no reason to reroll and it opens up the possibility of cheating/abuse we should not bother with the reroll.

:nono: Well, other than the rules and the possibility of getting a different result regardless of what the probabilities are, no, I guess not...............

ChaosRedCorsairLord

· #55 · Jul 16, 2010

don_mondo said:
:nono: Well, other than the rules and the possibility of getting a different result regardless of what the probabilities are, no, I guess not...............

There is absolutely no probability difference between the two. None, nada, zilch, zip, ninguno, aucun...

There is also no advantage of rerolling all of your dice, unless you are looking at you first results then deciding whether or not to keep them or to reroll. In which case you are cheating.

If there is no difference between the two why bother? Because GW told you to? Because it's in the rulebook? God forbid we use some common sense now and then, the hobby might actually get better. We might learn something. We can't have that.

lokis222

· #56 · Jul 17, 2010

ChaosRedCorsairLord said:
Because GW told you to? Because it's in the rulebook?

Yes because you always re-roll. You can make a house rule to do otherwise, but as the rule stands, you re-roll. To not do so is not supported by the rules. However, You Can Choose To Not Do So If Your Opponent Agrees.

darkreever

· #57 · Jul 17, 2010

I'm sorry, I feel like I'm missing something here. Are you saying that the rules state you must re-roll, regardless of the result? If that is the case, then where may I find this because it seems to be contradicting whats written on page two of the rulebook.

lokis222

· #58 · Jul 17, 2010 (Edited)

darkreever said:
I'm sorry, I feel like I'm missing something here. Are you saying that the rules state you must re-roll, regardless of the result? If that is the case, then where may I find this because it seems to be contradicting whats written on page two of the rulebook.

No. Sorry. What I meant is that if the rule calls for you to re-roll, you re-roll. Not that you re-roll a re-roll. There is no page two contradiction. However, the wording of page 2 says to do so if you wish to re-roll, whereas, at least in the case of the swarmlord, you must re-roll.

With the swarmlord, if a person in CC with it passes an invulnerable save, you re-roll. From what I understand, with the eldar thing, when you fail an invulnerable, you re-roll. So regardless of the initial roll, you re-roll. That is all this is being said. Not that you re-roll a re-roll.

darkreever

· #59 · Jul 17, 2010

I was more concerned about you possibly taking the stance that no matter what, if something has a re-roll it must re-roll regardless of whatever the result may be.

I play a lot of armies, so unlike other players, who play fewer armies, I tend to forget specific abilities and rules and what the exact wording for them may be.

From what I was reading, I got the impression that, in the case of the swarmlord if you took four wounds and passed three invulnerable saves you were saying that all four dice must be re-rolled, not just the three that passed.

lokis222

· #60 · Jul 17, 2010

darkreever said:
I was more concerned about you possibly taking the stance that no matter what, if something has a re-roll it must re-roll regardless of whatever the result may be.

I play a lot of armies, so unlike other players, who play fewer armies, I tend to forget specific abilities and rules and what the exact wording for them may be.

From what I was reading, I got the impression that, in the case of the swarmlord if you took four wounds and passed three invulnerable saves you were saying that all four dice must be re-rolled, not just the three that passed.

No, not at all.

k:

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