Are these "red flags" for you?

[Indefragable]

As others mentioned, I would stay clear of accusing him of anything. This isn't a witch hunt (is it a witch hunt? If it is then I need to go change and grab my pitchfork).

 

First rule of diplomacy is always to be well, diplomatic. Second rule is to establish fair and neutral terms that both sides can agree to without hesitation.

 

Set precedence by picking a section of the board where everyone rolls their dice and also establish that dice are not touched once rolled until both sides have had the option of seeing the result for him/herself. It can slow things down a bit, but once you get in the habit it can actually make things go quicker.

 

I also tend to talk out intentions and measurements and the dice rolls needed for certain things. I.e. "this guy is measured to be within 2" of your unit. Therefore, when it comes time to charge, he can't fail unless you have some special modifier. Agreed?"  That way if Shrek walks buy and bumps the table and suddenly your guy is 2.5" away, you've both already established that your intention in the movement phase was to be auto-charge distance and already agreed upon. Etc....We've also at times swapped Codexes before a match so that at any time you or your opponent can reference something you're doing....or is more often the case, simply learn about an other army.

 

Stuff like that can't change dice rolls or stop all shady behaviour, but I find it keeps both players on the same page and sets a "clear the air" precedence early and often.

[Rogue]

I also tend to talk out intentions and measurements and the dice rolls needed for certain things. I.e. "this guy is measured to be within 2" of your unit. Therefore, when it comes time to charge, he can't fail unless you have some special modifier. Agreed?" That way if Shrek walks buy and bumps the table and suddenly your guy is 2.5" away, you've both already established that your intention in the movement phase was to be auto-charge distance and already agreed upon.

And it’s cousin, “These guys are positioned 19 inches away from those, so you can’t move up and rapid fire them. Agreed?” It helps prevent any over-generous measurements in the subsequent movement phase.

[Lord Raven 19]

Maybe it would be worth just honestly asking him to roll where you can see

I agree on the DG dice though ugh, nurgle's blessings

[Kassill]

My main question is "Are you Wil Wheaton?" 


Otherwise anyone is free to roll my dice that I bring. I typically don't prefer to roll other peoples dice myself,  but I will usually ask beforehand if one of theirs happens to be closer and we are at an event or something trying to speed up the game. 

I don't perceive what you described as blatant cheating on the count of the dice, however I would call out anyone for rolling behind objects etc where the result isn't plainly seen. We had a guy years ago that played Guard and he could scoop up his dice as quickly as he rolled them and got berated for it repeatedly till he stopped coming. It's one thing to play efficiently, especially for timed events, but that was unacceptable behavior IMO. 

Like others said, ask around to see how he and the dice performed in other games and maybe request the organizer/store to  provide neutral dice for you both to share next time. 

[Indefragable]

Checking a dice roll is kind of a universal right for both players, IMHO. It's the closest thing to the official time/score up on a big 'ol scoreboard that we have.

[Lysere]

Who makes Gravity Dice ? Sounds cool.

 

Gravity Dice is the company. Precision machined metal dice. Personal suggestion is get the case as well. Magnets in both halves to keep closed and a bag to carry the case in for only a little bit more if you get a set of 6.

[BLACK BLΠFLY]

I ordered some this evening. Super stoked !

[sarabando]

Il send Childenuff from my local club round to play with his dice there will be no more 5s and 6s XD #cursedtouch