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Brewing Polyjuice Potion

From lacewing flies to someone else's face.

The case

Polyjuice Potion is a month-long project with no room for shortcuts. The lacewing flies alone take twenty-one days, and everything that follows depends on that stewing being done right. It’s the kind of undertaking where you can’t start late and catch up. The calendar is the calendar.

Most failed attempts don’t fail at the brewing stage. They fail at sourcing. Bicorn horn and Boomslang skin are controlled ingredients for good reasons, and acquiring them from a restricted potions store without authorisation involves its own logistical sequence that needs to be planned separately and executed without getting caught. The brewing is straightforward. The supply chain is the hard part.

The potion also punishes the one mistake that seems too obvious to make. Adding the wrong biological material at the final step doesn’t just fail — it fails spectacularly and painfully. It’s the kind of instruction that feels insulting to include until you’re the person who didn’t double-check and is now growing a tail.

Polyjuice Potion

  1. Gather lacewing flies. These need to stew for twenty-one days. Everything else waits for them, so start here.
  2. Add lacewing flies to the cauldron and begin stewing. Low heat. Twenty-one days. Mark the date.
  3. Acquire leeches. Twelve should be sufficient. Store them alive until needed.
  4. Acquire fluxweed. Must be picked at full moon. Check the lunar calendar and plan accordingly.
  5. Acquire knotgrass.
  6. Acquire powdered horn of a Bicorn. Not easy to come by. Begin sourcing early.
  7. Acquire shredded skin of a Boomslang. Likely requires access to a restricted potions store. #6 and #7 may need to happen at the same time depending on your access.
  8. On day twenty-one, add leeches and knotgrass to the stewed lacewing flies.
  9. Stir thoroughly and add fluxweed.
  10. Add the Bicorn horn.
  11. Add the Boomslang skin.
  12. Stir until the potion reaches the correct consistency. It should be thick and dark. If it's thin or the wrong colour, something has gone wrong upstream. Do not proceed.
  13. Decant a single dose into a goblet.
  14. Add one hair from the person you wish to become. A hair. Not a cat hair. Confirm the source. This is not the step to get wrong.
  15. Drink immediately. The taste is terrible. The transformation takes about a minute. The effect lasts one hour.

Make it yours

The twenty-one day stewing period is the constraint everything else is built around. Use those three weeks to source the harder ingredients — Bicorn horn and Boomslang skin are not the sort of things you find in a standard student cupboard. If you need to borrow from a restricted store, plan the acquisition carefully and well in advance.

The fluxweed timing is the other hard constraint. It must be picked at full moon, which means you need to align your brewing schedule with the lunar calendar. Start the lacewing flies at the right time and the full moon window falls naturally within the twenty-one days.

This potion is, objectively, above the skill level of most second-year students. If you're attempting it, you either know what you're doing or you're unusually determined. Either way, follow the steps. Improvisation in potions-making tends to end in the hospital wing.

The final step is the one most likely to produce catastrophic results if done carelessly. The hair must be from the target person. Verify your source material before adding it to the potion. Cross-species contamination is not reversible with standard remedies and will require professional medical intervention.