MathHammer - Charging off Deepstrike

Turn 3, I drop my grot bomb down, they need to make a 9" charge. What are my odds?

Well I calculated it as 56.84% chance of getting into combat. This assumes that if your first roll doesn't make it, you will either use our PFP to re roll both dice or use a CP to re roll one die. If you roll anything 4 or better, and still don't make it, keep the 4+ and reroll the other die.

This isn't as good as I had hoped, but if you bring two grot bombs, one is going to get in most likely.

Ignore the following if you dont care about the math:

So heres how i calculated it, i'm not a math wizard so please correct my math.

I wrote out every dice combo tolling two dice (36 results), then figured out what was the best option (re roll both or just one) and calculated what the chances of making successful charge was off that second roll. eg

The categories and their weights are: PFP re roll (27.7%*9) + first die is a 4 (33.3%*7) + first die is a 5 (50%*6) + first die is a 6 (66.6%*4) and successful on first roll (100% * 10).

This gives you 20.464/36 = 56.84% chance of getting into melee round 3 with a potential CP re roll off of a webway.

reroll charge range rerolls both dice only is it not?

Although I can see the argument of you "may" reroll your charge distance

I get marginally different numbers to you (56.94%) for the odds of a 9" charge with the command reroll.

Agree with your conclusion. If the highest roll on a failed charge is a 4+, then you should use a command reroll, and if it is 1-3 then you should use power from pain to reroll both.

If one dice is a 4 and the other is a 1-3, the command point only has a 1/3 chance of success. While mathematically more likely, the chances are still low and it is more likely to waste a command point. I'd be tempted to just use the pfp reroll.

No reroll
- You have 10/36 chances to succeed at first, rolling a 9 or higher on 2d6 => 27.7%

PfP reroll (so both dice) :
- If you failed and rolled double 1, spending a command point to reroll a single die makes no sense, and you use your PfP reroll to get another 10/36 chance (27%), for a total of 620/1296 => 47.8% (chances of succeeding a charge, if you include both attempts).


Command point reroll (1 die) :
- You have 1/36 chance for your highest result to be a 1, which gives you 0% chance to succeed with a single reroll.
- You have 3/36 chance for your highest result to be a 2, which gives you 0% chance to succeed with a single reroll.
- You have 5/36 chance for your highest result to be a 3, which gives you 16% chance to suceed with a single reroll
- You have 7/36 chance for your highest result to be a 4, which gives you 33% chance to suceed with a single reroll
- You have 9/36 chance for your highest result to be a 5, which gives you 50% chance to suceed with a single reroll
- You have 11/36 chance for your highest result to be a 6, which gives you 66% chance to suceed with a single reroll

Overall the single die reroll becomes better than the global reroll when your highest result (the one you don't reroll) is of 4 or more (which is extremely logical, since it's at that point that it's considered above average).

HOWEVER : if your highest result is a 4, the chances you'd get by spending a CP to reroll the other die are 33%, which is only 6% higher than what you get for free when rerolling both dice. So you are spending 1 CP (and preventing yourself from using that stratagem again in the same phase) to get an extra 6%... which is rarely worth it.
If your highest result is a 5, spending a CP increases your stats from 27% (total reroll) to 50%, so +23% (almost doubling the odds). Which looks a lot better.
If your highest result is a 6, spending a CP increases your stats from 27% (total reroll) to 66%, so +39%, which is incredibly worth it.


So i'd suggest only spending CP on charge rerolls if you roll a 5 or a 6. 4 is arguable, but i feel a CP is worth more than a mere +6% success chance.

EDIT : double post..

You only need an 8, not a 9.  because then you'll be right at the 1" from your opponent.


The reason to spend the command point if you have a 4 on the first die, is that your odds of rolling lower than that 4 on the re-roll are higher than rolling higher than the 4 on the re-roll.  (I suppose that would mean that it is a 50-50 shot to roll lower vs. equal to or higher).

Silverglade wrote:

You only need an 8, not a 9.  because then you'll be right at the 1" from your opponent.

No, you have to be more than 9" away so if you roll an 8 you are still more than 1" away. It's a 9" charge.

Silverglade wrote:

You only need an 8, not a 9.  because then you'll be right at the 1" from your opponent.

If you roll 8, you are 1.1 " away from target.

Quote :

The reason to spend the command point if you have a 4 on the first die, is that your odds of rolling lower than that 4 on the re-roll are higher than rolling higher than the 4 on the re-roll.  (I suppose that would mean that it is a 50-50 shot to roll lower vs. equal to or higher).

Indeed, rerolling a single die is beneficial if you rolled a 4. But it's not VERY beneficial (read previous post to see why), and i costs you a CP. So it's, arguably, not worth the cost at all. And it deprives you from the possibility of rerolling another die in that combat phase, which is a big deal.

I hadn’t thought about the cost benefit ratio, that’s a good point

If I were to use the grot bomb, I’d probably want to have two groups of 5, on the first charge I wouldn’t use the Cp for a 4, but on the second I would because if you don’t get them into combat it’s a lot of CP and points that didn’t get into combat when you needed them

With mandrakes however, I’d just run lots of minimum squads and just use the PFP re roll

All and all, I think grot bombs may not be worth it, and maybe deep striking something else in would be more ideal.

There is a big problem in that a lot of games can be decided by turn 3. Having that many points invested into that point of time is horribly risky all for a reroll to your charge distance.

Sadly I don't believe webway portals will have the best use for deepstrike assault without additional help or perhaps a word of the pheonix cast for movement. The crappy problem with this is if we think of the issues scourges have with deepstriking its that our best shooting like ehatlances or dark lances don't use it well and the army is quick enough to get most blasters in range without it.

We invented the webway portal and deepstrike shenanigans and now are the worst at using it

Not really. You have 48% chance to succeed a DS charge turn 2. Many armies don't have such good odds. Some have it even better, but we're definitly not the worst.

Plus, deepstriking isn't only about charging or getting in range. It's about protecting your board from alpha striking, leaving only your expendable/tough nuts on the board. And that ability is amazing (it's the best use scourges can make of their DS anyway).

I have to agree that Heatlance's range being increased by 1" would suffice to make that weapon viable, since not being able to DS in melta range kinda renders it useless.

I wouldn't invest the points into grotesque units for less than 50 percent, especially turn 2. It will be great for making a line of kabalites away from your main army, and heaven forbid kabalites get a buff like +1 to wound with poison

I'd suggest that if you really want a charge to go off, you should bring three units not two. Since the maths seems to give around a ~50% or so chance for each charge being successful, then with two units 25% of the time neither will get in (50% one, 25% both). And failing completely every 1 in 4 games is pretty bad.

If you bring three units then it's only 12.5%, 1 every 8 games, that completely whiffs. So 7/8ths of the time you will at least achieve something.