Monk / Stonebrawler Mountain Stance / Stonestrike Stance in Starfinder 2e.

[Eternaldoot]

Stonebrawler in AP 195 and Mountain Stance in PC2 both have a requirement related to ground. Touching Ground for Mountain Stance, and Standing on Ground for Stonebrawler. Would any load bearing structure, such as stone tiles on a roadway, the surface of a asteroid, chunk of broken planetary material, natural satellite or the floor of a craft be classified as ground for the purposes of Stonestike stance and Mountain Stance?

Ground by definition is classified as the surface of a planet, and a planet is classified by 3 things. 1. its orbit around a star (its why moons do not count as planets). 2. It must have enough gravity to force it into a spherical shape. and 3. it must be big enough that its gravity has cleared away any other objects of a smaller size near its orbit around the sun. (as defined by International Astronomical Union)

This means the many moons in starfinder, any floating shards of Acturn, and any other natural satellites do not function as ground for Mountain Stance/Stonebrawler.

[Finoan]

If you want it to work, you don't want to go with a word-definition type of argument here. Go instead with a game balance type of argument.

Is it really necessary for game balance? Is Mountain Stance really so powerful that it needs a ruling that causes it to not work in the large majority of terrain environments of the adventure?

It really isn't all that powerful. The AC that it allows isn't any better than other AC values that can be gotten by other characters. What its purpose is, is to allow a strength-based martial character that doesn't use Armor items. There are other ways of accomplishing that, to varying degrees of success. Mountain Stance has its own limitations that it imposes - it doesn't do so well once the PCs and enemies have access to flight, for example (which happens very quickly in Starfinder).

So the nerf ruling isn't really necessary. Yes, it says "ground". No that does not necessarily mean "dirt". Any permanent terrain that supports the character's weight should be able to qualify. That doesn't break game balance any.

[YuriP]

Exactly; I’ve seen interpretations where ships aren't considered "ground," but honestly, that’s an overly restrictive take on the stance. My impression is that it’s about being on a solid, stable surface—not necessarily the actual ground of a planet.