Aurifer is the final form of the late-game knife in Desiderium. Starting with the Lapis Fictus Knife, refine it through electricity, mercury and moonlight. The resulting knife also makes the Relicta choice important: preserve a save before using it against them.
Where this guide starts
This route assumes you already obtained the Lapis Fictus Knife from Ivan’s statue in Desiderium. The earlier vase, figurine and Auritsatio preparations are outside this page’s step-by-step coverage. If you only need the chemical substance for the first Study Door, use the early chemical puzzle guide; it is a different objective.
The three transformation checkpoints
| Starting item | Station | Expected result |
|---|---|---|
| Lapis Fictus Knife | Desiderium kitchen fuse box | Melanosis Knife |
| Melanosis Knife | Mercury pool below the elevator-shaft route | Viridis Knife |
| Viridis Knife | Hotel door reached using the Lead Key | Aurifer |
Read the item name after each station. Moving on with the earlier form is a clearer sign of an incomplete interaction than the room’s appearance alone.
Refine the knife
Reveal the full upgrade route
- Take the Lapis Fictus Knife to the kitchen fuse box and use it there. It becomes the Melanosis Knife.
- Return to the open elevator on Floor 2 and descend through the shaft route. After the fall, escape the Relicta and continue to the room with the two statues on the bed.
- Use the Melanosis Knife in the mercury puddle near the television. It becomes the Viridis Knife.
- Interact with the exit hole in that room. The television/VCR releases the Lead Key; collect it before leaving.
- Return through the stairwell to the Floor 2 hallway and enter the door left of the elevator. Use the Lead Key on the northward hotel route.
- Continue through the hotel to the save point and the marked door. Save, then use the Viridis Knife at that door. The moonlight sequence yields Aurifer.
- Save again in a separate slot before choosing how to treat the Relicta.
What Aurifer changes
Reveal the ending-sensitive use
After Aurifer is obtained, killing a Relicta with it sends the finale toward MAGNUM OPUS. Passing them without those kills preserves SOLVE ET COAGULA. The condition concerns this late-game Relicta choice, not every earlier mandatory monster fight. See the ending overview before using the knife aggressively.
Common points of confusion
Where is the moonlight interaction? Follow the Lead Key route to the hotel’s marked door. You do not finish this knife simply by revisiting the original bedroom’s sunlight.
I have Viridis but no Lead Key. Recheck the hole interaction in the mercury room and the television/VCR reward before leaving the area.
I want both main endings. Keep the branch save before any Relicta kill. A save made after the choice cannot restore the earlier state by itself.
Evidence and limits
The transformation sequence is cross-checked against Into Indie Games and Gamer Social Club’s release-build routes. Exact installed build, alternate path behavior and console parity remain unconfirmed. This page explains the refinement segment, not a complete Desiderium walkthrough.
Sources & corrections
This guide is written from the sources below and reviewed for consistency. We do not claim a personal playtest. Exact game build numbers were not available for every source; follow the stated full-game or demo scope.
- Into Indie Games — Desiderium and ending walkthrough ↗
- Gamer Social Club — full puzzle walkthrough ↗
- Prima Games — full-game walkthrough ↗
- Destructoid — all endings and hidden routes ↗
Checked on 2026-10-23. Found a different result? Send a correction with the guide URL and game version.