Jump to content

Damage dice re-rolls. When should you?

chapter master 454

Recommended Posts

So as of late, there is one thing I have been running through my head while I drive buses (can't have music so musing on 40k based things has to do!) and one of the key things I have currently got hung up on is in relation to the fact grav-cannons can get re-roll damage dice. Not exactly a common re-roll type to get en mass, normally its a "re-roll 1" or "roll 2d6, take highest" sort of thing but this is kind of weird because now we have a question (well I do but I wonder how you guys see it).


What numbers do you re-roll on the dice?


So in terms of the grav example, when it gets to roll D3 damage vs. a 3+ save unit we have 3 results. 1, 2 and 3.

We will ALWAYS re-roll 1 and never re-roll 3.

The objective is to achieve maximum damage, not any break points. For all purposes of this question, the target will not be bracketed, killed/destroyed, stopped or hindered by the rolls no matter their number however you are simply seeking to do as much damage as possible within rolling your set of D3s, allowing for 1 re-roll per die (so no re-rolling a re-rolled die as per usual).


I am personally coming to the conclusion is that you should re-roll 2s. After all, if we are playing odds then odds should favour you re-rolling 2s since 2 outcomes don't hurt you out of 3 (and 1 even benefits you). However when running some really quick maths in my head (remember...driving buses, not sitting in an office!) it however would appear that re-rolling 2s would however only end up just being the same overall.


I did run this idea against D6s but I quickly considered that question far less interesting as the % stay the same really as I concluded it is best to re-roll 3s and less.


So I put it you my fellow fraters, whats your conclusions?

Link to comment
Share on other sites

The average damage is identical whether you're rerolling only 1s or rerolling 1s and 2s. Rerolling 1s gives a more consistent 2+ chance, while rerolling 1s and 2s spreads a bit higher and lower.

Rerolling 1s gives a 4/9 chance to roll a 3, 4/9 for a 2, and 1/9 for a 1

3x4/9 + 2x4/9 + 1/9 = 7/9, or 2.333 avg damage


Rerolling 1s and 2s gives 5/9 to roll a 3, 2/9 for a 2, and 2/9 for a 1

3x5/9 + 2x2/9 + 2/9 = 7/9, or 2.333 avg damage


If you need to roll 2+ for 2 wound models, reroll 1s. If you need to roll 3+ for 3 wound models, reroll 1s and 2s. Otherwise you could try to work out on the fly whether you need more 2+ or 3s based on what you rolled vs wounds left on the target. Or just stick to rerolling 1s since it's faster.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.