Looked at it. Seems to do what I want, not quite the way I want but it's more preferable than slimshrooms. I don't know why I didn't find this one when I was combing the www for some help with my idea, but I am glad that you found it! Thank you so much!

@Noranum I just remembered that there's a mod called "VSR - Regenerating Monsters" that allows plump helmet men to regenerate limbs. It applies the syndrome with an interaction rather than a secretion, which avoids the whole slime thing altogether.

I'll give it a try, thank you for your response and advice! :D
I tried to tinker something like this a year or so ago, but stopped cause it didn't work in a way I was happy with. I thought maybe you had found a way that I would have never be able to come up with but if I remember correctly, I already walked down the syndrome path and ended up with slimy little mushroom men... Maybe I just have to wait until the game itself supports regeneration without syndromes.

@Noranum You can use SYN_AFFECTED_CREATURE to make the syndrome only apply to a certain creature.

Yeah that basically is a problem since the mushroom dudes don't have... anything, actually. No organs, no heart, no blood, not even eyes to shed some tears (given the fact how most dwarves view them as walking food, maybe it's better that they can't cry).
It can't be internally, then, so I would end up covering them in this stuff which probably would apply the syndrome to people touching it, right?
If I remember correctly, the last time a tried something like this I ended up having the entire map "infected" by self-healing :D

@Noranum Of course, looking at other people's raws is a great way to learn modding. You should be able to make a syndrome similar to the one above that regrows limbs by using CE_REGROW_PARTS instead of CE_HEAL_NERVES, and then you could give the desired creatures a secretion that continuously applies the syndrome to themselves. There's an example on the wiki for what that would look like on this page you could look at: https://dwarffortresswiki.org/index.php/Syndrome_examples#Creatures_that_behave_differently_underground

I've been looking for some time now for a way to implement something similar to normal tissue. In short, I tried to allow Plump Helmet Men (and any other creature that uses the plant tissue template) to regrow lost limbs (happens so often because they have no bones or any layered tissue). I failed so far. May I poke around in your raws?

Indeed. It does a lot of Tarn's work for him (which is very good), in adding more content or for balancing aspects of gameplay. I know I've been looking forward to messing with mummies; it'd be cool if a raid didn't inevitably end in a permanent curse. Maybe just some horrible prolonged sickness or an very high likelihood of unfortunate accidents for a while.

@Digganob For sure! Any additional modding possibilities go a long way for this game. I'm excited to see what people do with the moddable procedural stuff from the Lua beta.

I see. So that revised version isn't viable, that's a shame. Interesting research, though. I hope we'll have stronger modding tools later, for messing with things like body mechanics and physics more deeply.

@Digganob It's the same as the one in this mod except it's SEV:1 and START:1 (and therefore has a duration). Unfortunately through some more thorough testing I discovered that SEV for CE_HEAL_NERVES just seems to act like another timer (with 100 triggering immediately on the START tick and 1 being roughly 3 real-time minutes after the START tick), and once it triggers the creature will heal all nerve damage it has instantly, and also heal any additional nerve damage it takes instantly for the remainder of the syndrome's duration. So it just ends up being more intrusive/exploitable than this mod's version with no upside.

I am certainly interested. What does the raw look like for this revised version of yours? Why would it have to be permanent?

If there's interest in the revised version I'll probably release it as a separate mod rather than an update to this one. I don't see either as strictly better and I prefer this version personally.

I made a revised version of the syndrome that starts immediately after injury and works over time, which has pros and cons over the current version. The benefit of that implementation would be that it would ensure nerves always take a consistent amount of time to heal, but the downside would be that it would either have to be a permanent syndrome or nerve damage that happens toward the end of the timer would fail to heal. It's also worth noting that the slowest possible "gradual" (I put that in quotations because it's still effectively an instant heal when the effect has been around long enough to work because there is no such thing as a partially-healed peripheral nerve in the game) speed seems significantly faster than the current 2 week timer variant but it's difficult to test how long it takes exactly.

Testing this out!