I have a character that focuses on torture (usually on the more medical side/using medical instruments) and i wanted to know if i could get tips for writing a sadistic character and well written gore
I think for me as a reader, the gore that tingles my amygdala is the kind that doesn't go too graphic, but is more stark and clinical. That gives it a feeling of detachment and that then plays into the psychological effect being tortured has. Medical torture would fit with that, I think, because someone with certain familiarities would be able to wield a scalpel, for instance, to cause maximum pain and suffering while knowing how to prolong the torture. Now that I've typed all of this, I don't know if I've answered the question, but there is my answer.
Haruki Murakami has a scene in The Windup Bird where its this old man recounted his time in the war (I forget which one where one of his fellow soldiers is being flayed. before it happens, the Russian captor explains to them in detail what is going to happen to them and how meticulous it will be. and then it happens. even though its to torture someone into talking... there is a surgical/procedural way its described. I couldn't listen to it all in one sitting. But, if you are wanting to read it for research, it happens in Part 2: Chapter 1
Perhaps medical books on surgery/anatomy and possibly even those Youtube surgery videos if you can stomach them.