Criticism
First a couple questions:
A) Is lay on hands/inflict w/ hands based on ranks or total bonus?
B) Why do you have stat restrictions for a prc? Do you think a low-self esteem yet extremely knowledgable druid wouldnt make it as a black healer? What about a bumbling ranger? Ok, I agree with the ranger, but a better way might be ranks in Wilderness Lore, after all you have to navigate through a swamp (and it may take a few days to find the lair) and you wouldnt want someone who would get lost.
C) Why isnt profession (or even just profession (herbalist) on the class skill list?
Ok, I see this class as underpowered, but teeming with flavor. As far as who would take it? I'd say multi-class barbarians, rangers, and druids, possibly some extremely devoted clerics (to weird gods). And heres why its underpowered (based on who I think would take it):
1) Mutli-Classed Barbarians - barbarians are into the mysticism thing, and being suspicious of civilized things in general lends them to searching out "her". However, they give up hp, bab, and barb stuff. Naturally, any way you slice it theyre giving up barb stuff, but the black healer seems like a (generally) suspicious person, maybe uncanny dodge? The heal skill ranks make it difficult for a barb to enter, but a multi-barb might be able to.
2) Rangers - This appeals to rangers a la wilderness thing, they lose out on spells, a little bab, animal companions, and favored enemy. Nothing you can do about most of that stuff, but have you considered a beast or maybe magical beast companion (which must come from terrain: swamp or underground)? You could let druid or ranger levels stack for the HD of the companion.
3) Druids- This seems like the most likely class to take this prc. They have a healthy respect for nature, try to preserve some sense of balance (as black healers try to heal/save some group of people), and most of the progressions are exactly the same. If you wish to avoid spells, making a companion fo some kind (not necessarily animal, but I wouldnt go better than abberation, beast, or magical beast) seems like a good way to keep the abilities you want while powering them up. As earlier suggested perhaps allowing druid to turn into abberations, beasts, or magical beasts at higher levels (without adding additional wildshapes) could be an interesting lure for druids. For non-druids, allow them to wildshape as a druid 1/day. This would make a good higher level ability, imo.
4) Clerics (the weird devoted kind that take things like ooze-master) - The nice thing about clerics is they are almost always happy as long as they get nifty abilities and spells. Oh wait, no spells. I can see a cleric bouncing a couple levels of this prc, but there would have to be something pretty tantalizing near the end for them to give up 10 levels of spellcasting. Of course, the black healer is constantly drawing on life energy (a form of magic) so maybe you could increase their caster level for the purpose of making magic items? This might appease the truly fanatical clerics who may otherwise not go for it because of no spell progression.
Those are my suggestions based on who might take it, here are some general suggestions.
Fear Resistance should eventually become Fear Immunity.
I dislike Fast Healing. I dont think there is a single magic item which gives this ability, and even the spells that resemble it are very high level. I would advocate Acid Resistance or even Damage Reduction (for those potential barbs) before Fast Healing.
Overall there is not much that affects combat. Fast Healing is about the only ability that would come into play, the rest is all roleplaying and minor bonuses. If you have a heavy roleplaying game, this class may already be balanced, but if your campaign is more hack n slash, dont expect anyone to jump at this class. I like it a lot, but my suggestions were geared towards making it more "3rd ed" and less original.
To sum up: It needs more abilities that are geared towards being more productive/increase survivability during combat. Uncanny Dodge, a Special companion, Acid Resistance, and replacing Fast Healing with Damage Reduction are some of my suggestions. Im not saying incorperate them all, but feel free to use any if you think they fit the concept.
Technik