The 8th level spell Clone requires a1in^3 block of flesh. Where do you think is the best place to take it from, in terms of pain, recovery and physical interferrence?
You don’t want to sever anything, as you would need a regenerate spell to restore that. Taking it from too close to an artery or major vein would be a problem.
A person would have to be fairly fat to get that removed from something like a shoulder. It seems to me like arm or leg muscle is the most viable place.
I don’t have experience about the topic but here I go -
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If humans only are available for extracting muscle?
I agree on the legs and arms. From specific places where it causes the least damage, and from many people if able, to minimize damage even further.
If beasts were game for this stuff, then they would probably be priority above humans.
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I cannot avoid noticing how well this question fits in the realm of morbid curiosity!