I was trying to add a homebrew magic item into my game from a post I saw online. It's a cursed handaxe that has a special ability to do more damage, but when you do more damage you do 1d4 to yourself. Is there a way that I can make it roll the 1d4 along with the 1d6 for a handaxe?

Not yet.

So you can actually do this. Kind of. You make the weapon using one damage die. Then when you add it to your inventory, customize the weapon to add an additional die of damage. You can even make a note that it is self damage. This even works with Beyond 20. When you roll damage, the damage to yourself shows up on a separate line so you can just break it out from the normal damage roll.

please tell me how you do this godly task.

Quote from Odious_Botch >>

please tell me how you do this godly task.

 You can’t. You would have to make a custom action on the character sheet to do it. There is no way currently for us to program a homebrew to make the system to roll a d6 and a d4 at the same time. The Devs can’t even do it, or Chaos Bolt would do it. The Devs can also not yet get Flame Tongue Weapons to do it either.

I told you wrong. You can still get there, but not the way I described it. Here's what to do instead. Let's say you have a handaxe that does 1d6 slashing damage to the target and also 1d4 necrotic damage to you. Make your magic item and give it 1d6 damage like a normal handaxe. Then go into the modifiers and add a modifier to do 1d4 necrotic. Now when you use the dice roller in D&D Beyond or if you use Beyond 20 to send the roll to Roll20, the 1d6 damage will still process as normal with the proper modifiers, but it will also roll 1d4 necrotic damage on a separate line item that you can easily just apply to the wielder instead of to the target.

Quote from TexasDevin >>

Then go into the modifiers and add a modifier to do 1d4 necrotic. Now when you use the dice roller in D&D Beyond or if you use Beyond 20 to send the roll to Roll20, the 1d6 damage will still process as normal with the proper modifiers, but it will also roll 1d4 necrotic damage on a separate line item that you can easily just apply to the wielder instead of to the target.

 It may do that on Beyond20, but it most certainly will not do that on the DDB character sheet. The 1d4 will have to be rolled separately using the actual dice suite provided, or they will have to create a separate custom action on the character sheet and roll the damage separately there.

Yeah, IamSposta is right, It doesn't auto roll it sadly, but I appreciate all the help!

Oh that's unfortunate. Oh well, dice are still in beta. Hopefully they will add that functionality sooner instead of later because it relly is nice when it comes across as separate line items. Very easy to work with the numbers at a glance.

Just reading this thread now since i'm trying to get the eldritch claw to work but im just going to roll another 1d6 necrotic as another action rather than get it to work in the same roll

Any updates to this???

If there had been an update you wouldn’t be asking because you’re already be able to do it.

Here's to hoping this quality of life feature exists by 2062

I wouldn’t bet on it.

Just found this in looking for something else...  Homebrew weapons DO, in fact, roll more than one type of damage die at the same time now.  If you build a weapon, in Homebrew, and want it to do, say, piercing and thunder damage (but the thunder damage is for a reaction if your roleplay is blocking a melee attack on another creature's turn), you create damage modifiers for the piercing separately from the thunder damage.  In the Thunder modifier, you add a detail, for reference only, that it is on a reaction.  When the weapon is equipped, you will have the attack roll, and piercing damage roll as usual on the Attack section of the character sheet.  In the notes alongside the damage roll button, the Thunder damage will appear showing the die roll count for that damage.  Clicking the damage roll button will roll both the piercing and thunder damage at the same time.  They will appear on separate lines of the roll, and this applies using the Beyond20 addon to roll it into Roll20.  However, the onus is on the player to remember that the thunder damage doesn't apply if it isn't the reaction.  There is no way to create a separate button on the character sheet to show the alternate dice roll as a separate action for the player to perform.

Hope this helps anyone that sees this in the future.  Just some knowledge passed from an avid Homebrew-goblin!  Cheers!

Quote from MasterOfTheHighHand >>

Just found this in looking for something else...  Homebrew weapons DO, in fact, roll more than one type of damage die at the same time now.  If you build a weapon, in Homebrew, and want it to do, say, piercing and thunder damage (but the thunder damage is for a reaction if your roleplay is blocking a melee attack on another creature's turn), you create damage modifiers for the piercing separately from the thunder damage.  In the Thunder modifier, you add a detail, for reference only, that it is on a reaction.  When the weapon is equipped, you will have the attack roll, and piercing damage roll as usual on the Attack section of the character sheet.  In the notes alongside the damage roll button, the Thunder damage will appear showing the die roll count for that damage.  Clicking the damage roll button will roll both the piercing and thunder damage at the same time.  They will appear on separate lines of the roll, and this applies using the Beyond20 addon to roll it into Roll20.  However, the onus is on the player to remember that the thunder damage doesn't apply if it isn't the reaction.  There is no way to create a separate button on the character sheet to show the alternate dice roll as a separate action for the player to perform.

Hope this helps anyone that sees this in the future.  Just some knowledge passed from an avid Homebrew-goblin!  Cheers!

 
You are incorrect. That will ONLY happen if you are using the Beyond20 extension. It is not a function of DDB at all.