Ship of Theseus. Replace a prisoner's entire body structure until they're nothing more than a Vegetable made out of Pegs
Why I think this is a good idea:
- Your Medics can get in good training
- If the surgery went well then you get free body parts
- Your Sanguophages can drink from your wooden nuggets no problem
- If the operation failed, no problem, that Impid probably/would have burned down your entire field of drugs
- Technically your Peg Prisoner is still alive, so their tribe will thank you for patching them up
- You get to break a Geneva Convention or two