What classes/feats exist for a evil surgeon/fleshcrafter?

[Malphegor]

So I was recently listening to the dismemberment song by Blue Kid, and it got me wondering for a bbeg or a character: what feats and abilities exist to let someone turn someone’s body unwillingly into their plaything, to alter flesh, to paint a work of macabre art with muscle and sinew and fat layers as the canvas? To look at the very limits of flesh and spit im the universe’s eye and go ‘bad design. You require upgrades. How do you feel about venom sacs? You don’t have a choice, I just want to know how much anaesthetic to use to stop your resistance.’

Initial thought was grafts, probably being a racial emulation changeling to emulate being incarnate construct effigies (given it seems that most who do ill advised surgical proceedures on the living are not humanoid by default) of all the graft giving races maybe. Wyrmgrafter too. Make people winged half undead monstrosities with fire breath sounds fun. Maybe cyborgs too with warforged grafts.

Maybe an artificer because it’s still crafting and xp costs are a thing even if one has transference and willing minions to gather xp to fund one’s experiments?

Necromancy is probably useful with spell stitching and haunt shifting, and the mother cyst spells to keep people compliant and in service to me, amongst other players of domination and control. As it costs xp, maybe a death trap where the only way to survive is by becoming undead and the instructions to becoming a necropolitan is written in large friendly green letters on the wall of their timed murder cell? Which might kill em anyway but hey food for the living members of our monstrosities I guess

Beyond that not sure what else is out there offhand to really get wrist deep in someone and make them a horror show.

Transmutation spells are often short lived, but polymorph any object chaining to give them a better base form is probably a good start if one’s not wanting to improve their initial attractive qualities and just wanna make the worst mutated supermonster one can?

disease manipulation maybe useful? Without spending time teaching everyone to take cancer mage levels I suspect most diseases will kill their hosts.

probably gonna need some variant of Leadership to have a mongrelfolk igor to collect bodies and subjects to test upon.

[Bohandas]

Fleshwarper (Lords of Madness) - graft specialist, bypass racial prerequisites for graft feats
Cancer Mage (Book of Vile Darkness) - disease specialist
Pale Master (Libris Mortis) - self modification with undead grafts
Impure Prince (Magic of Eberron) - includes symbiont luring abilities
Renegade Mastermaker (Magic of Eberron) - cyborg
Blighter (Complete Divine)- actively anti-nature
psionic classes- use tattoos instead of scrolls for some reason

[Inevitability]

Nosomatic Chirurgeon lets you inflict any diseases that you've ever treated on people, many of which easily fit the fleshcrafter theme. The BoVD especially has some fun options. It does require being a lightfoot halfling, but perhaps you appreciate the ironic contrast. Things like Faceless Hate don't kill their hosts but subject them to horrifying transformations instead!

[Doctor Despair]

The willing deformity line would probably be fairly representative here. Worship an elder evil to get a bonus vile feat for free at levels 1, 5, 10, 15, and 20. Ragnorra seems particularly appropriate as an evil for this purpose: see page 97 of Elder Evils.

[Troacctid]

D312 has a Fleshcrafter wizard variant based on Frankenstein.

[ShurikVch]

Aforementioned Dragon #312 also includes [necromantic] feats; 4 of them - Heightened Agility, Heightened Strength, Uncanny Speed, and Vicious Claws - are work by surgically modifying bodies before the animation (required Heal check)

Dragon #359 has Craft (body modifications) skill

Nocturnal Sea Gazetteer includes Create Magical Beast and Create Aberration [Item Creation] feats - they allow to combine multiple creatures into one: like "Bear"+"Giant Owl"="Owlbear"

[SangoProduction]

Pathfinder, spheres of power, has Alteration sphere. Even some explicitly gruesome alterations.
Also numerous class archetypes, particularly when centered around the undead, feature something to that effect.

[Bohandas]

If you have access to the Gate spell you can gate in a Sibriex demon (Fiendish Codex 1) that can create multiple fiendish grafts within the spell's time limit for "immediate tasks" (and arguably does not count as a more involved task as this is a supernatural ability which the demon can use "without paying the requisite costs in gold or XP")*. This will likely represent a net savings in XP

*however the instant graft ability does have very limited uses per day, so the DM would be well within their rights to say that the sibriex doesn't have any uses available