The Tavern

Kobolds are one of the weaker species in the game, which would be fine if they weren't also one of the least interesting. See this thread for a good comparison of kobold to deep elf. Kobold's gimmicks are relatively boring. Small size serves to restrict player weapon options in return for bonus EV... but Halflings are the same size as Kobolds, and Tengu also get an EV bonus at xl 5. Carnivore is not unique to Kobold and the pretense that it's important becomes more absurd with each passing version.

Moving nightstalker from a ds random mut to a guaranteed mut on some species might be desirable because the mutation is both powerful and, for some players, very annoying (it makes autoexplore take forever, for example). As a guaranteed mut, at least you know what you're getting upfront, and it's easier to directly balance the mutation against other aspects of the species design. Kobold seems like a reasonably thematic choice for nightstalker in addition to being a species in need of a better niche.

The specific proposal is as follows: Remove the demonspawn nightstalker facet and give Kobold one level of the nightstalker mutation at experience levels 1, 13, and 26. Kobold apts could be adjusted afterwards, if necessary, or the mutation xls could be tweaked if nightstalker at xl 1 is unreasonably good or xl 26 is too late for rank 3.

To replace the ds facet, I would suggest developing a "hexes facet" featuring some combination of 1) AF_VULN melee; 2) hexes enhancer; 3) radius 1 permanent silence donut, but a full discussion of ds mutations is out of scope in this thread. If there's interest, I'll make another topic.

I think it's better to just give the full nightstalker effect at XL1. Concentrating power towards the late game is not something the game needs more of.

they could also be "mut-prone", with pemanent Evolve, or they get double effect from mut pots, etc

also, please get in my silence donut

I like the idea (and would be happy to implement it if there's dev interest.) Suggestion on XL thresholds: I think XL26 is a bit too late for the final version of this. It's not too hard to win the game prior to XL26, and even if you don't you're only getting to experience their final form for a small part of the game. I'd aim for getting it around the time people enter Depths (since that's about the start of the DCSS endgame.)

Median Depths-enter XL on Ko in recent games is XL 23.
Mean is XL 22.62.

I'd suggest moving NS 3 to XL23.

I'm assuming this thread is in response to the pull request proposing the same, which seems like it will get some dev attention after 0.25 comes out:
https://github.com/crawl/crawl/pull/1329

The only reason I can see to delay giving the full mutation at the start is that +150 stealth is very strong at the start of a game, but it'd probably be ok if a species was strong at the start of a game (see eg gnolls, vampires). Certainly I would prefer to get the full night stalker effect by lair.
Also, please don't remove the DS nightstalker mutation. It's one of the more interesting mutations to get

Wasn't aware that there was a pr already. Neat.

Nightstalker would definitely make kobolds more interesting. Foul stench and to a lesser extent thin skeletal structure would also make sense, but clearly not full ranks of both. Kobolds are tied to foul stenches, and it is possible the -1 los and +50 camo may be too powerful at level one. Also theme and lore wise kobolds are more tied to being smelly and thin than being nightstalkers or tied to the shadows.

At level 1 provide foul stench 1 and thin skeletal structure. Keep the mutation scaling for foul stench only. Foul stench alone is probably not too strong to be added in addition to nightstalker if it is kept at level 1 instead.

We could just remove the stealth bonus from nightstalker and give DS a new mut if we're making kobolds the nightstalker race.

New unique: Bob the Bold