I'm making a race with the ability to burn a foe or heal an ally as an action {{modifier:con}} times per day. 

The healing/damage done is {{modifier:con+characterlevel}}, but I can't figure out how to set this up as an attack/spell that displays on a character sheet.

Some help would be greatly appreciated. Thanks.

Since there’s nothing to actually roll, it’s not possible to display that as a rollable if I recall. You can set up the Action, but it’ll never display the damage along with the weapons, etc., since there’s no need for a button that interacts with the dice roller. Just using the snippet is what’s intended.

Thanks for the reply. What about getting it to display in the same way as an unarmed strike?

You would have to list Constitution as the Ability Score, with a Fixed Value of 1, and then [SAVE] the Action. Then you would have to add 19 level overrides to that Action, one for each level 2nd-20th, each with the Fixed Value increased by 1. If it’s gonna work, that’ll be how to make it work.

Thanks so much for the support. I've done that, but it doesn't seem to update with levels. I saw another post where you said to someone that it only really works when there's a dice roll involved. That seems to be the case here.

For now, I've taken off the base Fixed Value of 1, but added a level override for level 1 and added it there. The damage box is blank, but the snippet is correct, and if the back-end ever gets updated to fix this hopefully it will just start working.

Yeah, that’s kinda what I figured, that’s what I remembered anyway.

So I created a feat that allows players to use an action to cause a creature within 5 ft to take damage if they fail a saving throw. I can force the feat into rolling digital dice only on their character sheet, not just by default but by going onto their sheet customising it and clicking display as attack. (Taking the display as attack option in the homebrew editor doesn't seem to work).

How exactly did you set the Action up? What fields and dropdowns did you use, and what did you enter and/or select?

Alright, I think I know why. You have it set as a “general Action,” which theoretically aren’t supposed to be “attacks,” but you have to make it a general Action because if you designate it as either a weapon or spell Action then the system will automatically add the PC designated ability modifier (Dex in this case) to the damage roll. On top of that, since it requires a saving throw and not an attack roll, that’s another reason the system is disinclined to display it as an attack. I think you’re going to have to accept that it won’t display listed as an attack like you want unless the player purposefully customizes it on their character sheet.

I do have a few notes for you though if I may (the 3rd one might or might not be the most useful for you). Please take them as my just trying to be helpful as that is how it is intended:

• In the Description you wrote “Your touch disrupts the life force of other beings. As an action, you can choose a creature within 5 feet to make a Constitution saving throw.” That’s a bit confusing because you wrote “touch,” but then describe a mechanic that doesn’t usually fit with that. “Touch” ranged stuff always either requires the character to either “touch a willing creature” (or an object), or else make a melee spell attack to touch a hostile creature. If you’re sticking with the saving throw you might want to consider changing the description a tiny bit to read something like “You can disrupt the life force of other creatures in close proximity” or something else that doesn’t mention touching. (Either that or keep that part and change it from a saving throw to an attack roll, which would also trigger the system to automatically display it as a rollable Action for you too.)
  
  
• Your wording isn’t bad at all, but it could be a little tighter if you want. More importantly you’re missing a bit about needing to see the target or not, you didn’t explain how the save DC gets calculated, and as written it grants a number of THP = half the roll and not half the damage.
    • I mentioned the part about seeing the creature because the way they designed the game, the only times you can target a creature you can’t see are if you make an attack since you get disadvantage for not seeing them to represent their advantage from that fact, or with an AoE since that would negate their advantage from not being seen anyway. They never write anything that lets a creature directly target a specific unseen creature with an effect that forces it to make a save.
    • The part about how to calculate the save is pretty much always necessary unless it’s already been established elsewhere how that’s done. (Like how the Spellcasting feature explains it so the spells don’t have to, or how the monk’s main Ki feature does it so the individual Ki features don’t have to, or how the Battle Smith explains it under Combat Superiority so they don’t have to for each Maneuver.) But since this is a feat, and not part of a subclass or anything it kinda should really be stated to make life easier for the player.
    • The part about the amount rolled vs the amount of damage may seem like a distinction without a difference, but it’s not since the creature might have resistance or immunity to necrotic damage.
  
  If you wish, feel free to make use of the suggested change in the spoiler below as it also cleans up the inefficient parts too. (I took a chance and guessed at what to call the save DC, I hope I guessed right.). Or don’t use it if you don’t want to, that’s obviously entirely up to you.
  
  
• I noticed that you simply copy/pasted the description into the snippet field. For things like the action you have written that force a save instead of an attack, using a dynamic snippet is usually super helpful since the system is specifically designed to not list them as attacks on account of they technically aren’t actually attacks according to the rules. (No attack roll ya see.) By using a dynamic snippet it will automatically adjust the save DC for the player’s benefit. It can also allow you to rephrase it in a more concise way to make it take up less space on their character sheet. If you’re interested I included a suggestion for the snippet in the spoiler for you too, but again it’s your choice if you want to use it or not.

I hope I was able to help. 

Thats super helpful thanks! one thing I did do was in a prior feat was state the save DC's for this series of feats was 8 + proficiency + dex mod as it was a prerequisite. So the dynamic snippet will make it rollable?

Quote from Kyppo >>

Thats super helpful thanks! one thing I did do was in a prior feat was state the save DC's for this series of feats was 8 + proficiency + dex mod as its a prerequisite. So the dynamic snippet will make it rollable?

 
No. I mean, it might if you’re running the Beyond20 extension, I really don’t know since I don’t run it. What the dynamic snippet will do though is at least make sure it always displays the correct save DC in the text. And if the player checks the display as attack box on that Action on their character sheet then it’ll display just like it does when you do it.

If you really have your heart set on making it display the rollable automatically then what you can do is change it from a general Action to a spell Action, if I recall correctly that should work. It will however automatically add the characters Dex mod to the damage roll, so if you want to keep the average damage more or less the same you could adjust the damage from 8d8 to 7d8 so when the system adds the character’s Dex mod the 4.5 that would be the average result on that d8 you dropped will more or less wash out with the PC’s +3 - +5 Dex modifier(assuming their Dex is in the typical 16-20 range most folks usually go for).