This GM's ruling: "The simulacrum heals non-hp damage like the original does"
Were this GM to rule, like the question asks, that a simulacrum can only heal hp damage if a creature undertakes—in a fully-equipped magical laboratory—a complex process taking one day then spends 100 gp per hp healed (a point of contention as per this question), then this GM would also rule that a simulacrum recovers from everything except hp damage as per the original creature. That includes ability score damage (healed normally by most creatures at a rate of 1 point per day) and nonlethal damage (healed normally by most creatures—exclusive of it healing hp damage—at a rate of 1 point per hour per HD).
For example, a simulacrum of human wizard casts the spell fractions of heal and harm then follows that with the spell fireball. The fireball spell's damage is reduced, but the wizard simulacrum doesn't heal any hp damage that she's suffered. (And, as no hp damage was healed, the simulacrum's nonlethal damage tally isn't thereupon reduced.)1 To heal hp damage, that wizard simulacrum must itself—or find another to—undertake in a fully-equipped magical laboratory a complex process taking one day and spend 100 gp per hp healed.2
Spells like break enchantment, remove blindness/deafness, remove disease, neutralize poison, and even, to a degree, restoration et al. work normally on that wizard simulacrum in this environment. It's just that literally anything that would heal hp damage to a simulacrum simply doesn't unless it's that complex process.3
This ruling would come about because of the way I'd be reading the differences between the original creature and the simulacrum:
- The simulacrum "appears to be the same as the original, but it has only half of the real creature’s levels or HD (and the appropriate hit points, feats, skill ranks, and special abilities for a creature of that level or HD).… You must make a Disguise check when you cast the spell to determine how good the likeness is. A creature familiar with the original might detect the ruse with a successful Perception check (opposed by the caster’s Disguise check) or a DC 20 Sense Motive check."
- The simulacrum is "under your absolute command. No special telepathic link exists, so command must be exercised in some other manner."
- "A simulacrum has no ability to become more powerful [therefore i]t cannot increase its level or abilities."
- "If reduced to 0 hit points or otherwise destroyed, it [the simulacrum] reverts to snow and melts instantly into nothingness."
- Only a "complex process requiring at least 24 hours, 100 gp per hit point, and a fully equipped magical laboratory can repair damage to a simulacrum."
The addition of only in that final bullet plays a significant role in my decision, but even more important is the addition of therefore in bullet #3. I've personally started grouping those two statements since a deep dive into the simulacrum spell for Dungeons & Dragons 3.5 (see here), and nothing indicates that Pathfinder changed that detail of the simulacrum spell, so that should stand.
However, if a GM doesn't insert that therefore and bullets that item as two separate statements instead, then they look like this:
- "A simulacrum has no ability to become more powerful."
- "It [the simulacrum] cannot increase its level or abilities."
…And that's a whole 'nother thing. In addition to my research suggesting that they should be part of the same bullet—that the ability to become more powerful means a creature's capacity to increase its level therefore also increasing its ability scores—, reading A simulacrum has no ability to become more powerful as its own isolated idea may send ripples throughout the campaign that a GM should be aware of; see below.
An alternative ruling: "Things can only get worse from here"
Were a GM to rule instead that a simulacrum doesn't recover naturally from anything except hp damage (a reading that I'd personally find troubling were I player but not so troubling as to abandon an otherwise good campaign), that's the GM saying that A simulacrum has no ability to become more powerful means that a simulacrum has no ability to become more powerful (in the GM's opinion) than it is right now except insofar as a simulacrum can be healed of hp damage by the process the simulacrum spell describes.
This ruling will see the majority of the campaign's adventuring simulacra suffer gradual degradation that will eventually lead to them either retiring or rendered useless—for many game purposes anyway. That is, in such a campaign, a simulacrum's nonlethal damage can't be healed, it can't shake diseases, its ability damage never heals, and its blindness would remain despite a remove blindness/deafness spell or even fresh eyes from a regenerate spell (if that would normally be an improvement over the former, obviously). A GM could even go so far as to say that a simulacrum that suffers any negative impact from anything sees that impact never end, even after any associated benefits end! Since removal of any negative impact would make the simulacrum more powerful than it was before the impact ended, that impact just never ends. A simulacrum must be careful as one misstep can lead to an injury or condition that remains for its literal lifetime.4
In short, the GM could rule that anything that makes a simulacrum less powerful (in the GM's opinion) except hp damage occurs instantaneously therefore forevermore and that anything that makes the simulacrum more powerful (in the GM's opinion) just doesn't do so.
That's a bridge too far for this GM. First, that ruling has the potential of requiring tracking a lot of stuff that ends up not needing to be tracked. This GM doesn't want to have to track that Sivart dealt 2 points of nonlethal fire damage to Ekaj's simulacrum butler when Sivart spilt tea on him, for instance. Further, this GM can imagine arguments with players over what makes a creature more powerful, and the GM will be left making unilateral and probably unpleasant-for-PCs ad hoc rulings that must be recorded for consistency and verisimilitude. More importantly than all this, though, is that this ruling has a decisive impact on any campaign that plans to use frequently the simulacrum spell as a plot device or PC tool.
Let me explain: The simulacrum spell has a duration of instantaneous, so once the spell's resolved there's no magic to affect.5 Using the ruling that I just offered about forever damage, multiple ways of detecting simulacra suddenly present themselves: casting blindness/deafness on a suspected simulacrum then remove blindness/deafness on the subject is complicated, but bonking a suspected simulacrum on the head with a sap and seeing an hour later if the wound's healed is pretty easy. In fact, that's a duty militant city guards might be happy to perform on travelers before a traveler can set foot in a city once plagued by simulacra. In other words, simulacrum detection becomes an inexpensive, nonlethal task that can be carried out by untrained low-level folks. That's important: There are a lot of those, and they work for peanuts.
This means the simulacrum spell is now a terrible method of clandestinely inserting a spy amongst one's allies and opponents as the first time they engage in combat, some condition that the GM rules makes the simulacrum less powerful will undoubtedly be visited upon the simulacrum, and the simulacrum's identity is exposed as it can never become not fatigued or whatever, and that's pretty terrible. If the simulacrum spell is ruled to function in such a way, the simulacrum spell loses a lot of—but far from all of!—its appeal. For instance, a simulacrum probably becomes much more a tool for mad scientists holed up in their labs and rarely a tool for spymasters to use for infiltration and deception.
Another alternative ruling: "No healing for you!"
I can't know how a GM would arrive at a ruling like a simulacrum recovers from everything as per the original creature except damage of all kinds. That isn't, so far as I can tell, a reading that's supported by a text. That's okay. GMs have house rules. (And, again, this a ruling that this player would leave a campaign over.) However, if that's the ruling that's been made, then you must take up that ruling with the GM. Because there's no precedent for that, and because it's not a ruling that I can recall anyone having played under in the threads I've read about the simulacrum spell—which, honestly, are many—, I just can't know how such a creature would heal nonlethal damage and ability damage.6 In sum, if playing in a campaign under such a ruling, ask the GM.
1 This GM would not have that effect fail outright (see here), as if the simulacrum were an illegal target or something. The effect occurs, but the target's ability changed the result.
2 That it takes the same amount of time to heal the simulacrum of 1 hp of damage as it does 100 hp of damage is because the simulacrum spell says so. Yeah, I don't even. And—thank you for asking—, this GM would rule that the simulacrum must be present during the entire process. Ruling otherwise strikes me as both asking for trouble and deeply weird.
3 Notwithstanding further exceptions, plot devices, or unique effects. (For instance, an effect that said that it could specifically heal a simulacrum's hp damage would actually do so.)
4 This could get weird fast. For instance, a simulacrum that enters combat may find itself flat-footed forevermore!
5 The instantaneous duration of the simulacrum spell means that while the casting of a simulacrum spell can be sensed with a detect magic spell for a while after in the area in which the spell was cast, the result of the simulacrum spell—the simulacrum itself—is nonmagical and can't be detected with a detect magic spell.
6 I suspect, at the very least, that the GM will rule that a simulacrum heals nonlethal damage when it heals hp damage via the process the simulacrum spell describes.
Note: Despite at least one authority over the game's rules saying that he'd rule like the question about healing a simulacrum's hp damage (see here), this GM likely would not make the same ruling. Instead, this GM would likely rule that a simulacrum heals normally and can be healed by the special process.
