So I'm trying to make a snippet where it has a base value of 8, and takes away your con modifier. My current code is this: {{8-modifier:con}}; pretty simple. But I wanted to test it with a negative constitution modifier, and it only returns NaN; how do I get this to work?

Also on a side note, my original code looked like: {{(8-(modifier:con+((proficiency/2)@rounddown)))@min:1}} but that just spits out the error "rounddown)))@min".

Can any of you guys help with these issues?

What exactly are you trying to accomplish? If you just copy/paste the description of your feature/trait it’ll be easier to help you.

Right, my description is this (do note it still has the proficiency version because I wanted to make the cost of blood go down even if the con modifier wasn’t effected so that players could still feel stronger as they levelled):

You regenerate; regaining 2d4 + your con and proficiency modifier. You can use this an equal number of times to your proficiency bonus + constitution modifier every long rest. Every usage (but not charge) of Regeneration drains your blood by [8 - (Con Modifier + (Proficiency / 2 rounded down))].

So, if I May I’d like to reword it for clarity as well as help you with your snippets, I hope you don’t mind.

Description

You regain a number of hit points equal to 2d4 + your Constitution modifier + your proficiency bonus. You can use this feature* a number of times equal to your Constitution modifier + your proficiency bonus, and regain all uses whenever you finish a long rest. Every use of this feature* drains your blood by an amount equal to 8 minus the total of your Constitution Modifier + half your Proficiency bonus (rounded down).

Snippet

{{proficiency+(modifier:con)#unsigned}} times per long rest you can regain <strong>2d4</strong>{{modifier:con+proficiency}} HP. Each use of this feature* drains your blood by {{8-((proficiency/2)@rounddown+(modifier:con)#unsigned)}}.

*Trait if this is for a race instead of a subclass.

I think that should work, but if it doesn’t then post again in this thread and use this snippet as your starting point: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/25930-using-snippet-codes-in-your-homebrew).

So all but the signing seems to work, as it spits out this error. https://imgur.com/a/OozEPlL

Try this instead:

{{8-((proficiency/2)@rounddown+(modifier:con))#unsigned}}

It works; but do you know how to make it so that a minimum of 1 blood will be drained? I tried messing around with the @min:1 command but couldn't get it to work.

Try this:

{{8-((proficiency/2)@rounddown+(modifier:con))@min:1,unsigned}}

It gives the error:

Unknown value modifier type: unsigned

 I tried adding a # infront of unsigned but that didn't work either.

Then go to that other thread I linked for you, use the version that works but doesn’t have the min:1, and ask them there. That’s where the snippet experts lurk, that’s where I go when I need help with a snippet.