Fusion runs from the normal inventory — no station or workbench is required. Drop stacks into the Fusion source slots and the game blends their essence into a single output.

1. Energy sets the weight. Each source contributes energy × stack count. The source with more total energy dominates the blend.
2. Thirteen properties are averaged. Clay, phlegm, sulfur, mercury, aqua, utility, edibility, danger, wearability, blockiness, hate, lust and faith are mixed by that weight. Hate, lust and faith count roughly 1.4× as much; clay, aqua and blockiness count 0.75×.
3. Tags pull the result. Any item sharing a tag with the sources is pulled closer; an item whose output tags match the sources is pulled in hard — this is how special results are wired.
4. Colour nudges the match. The averaged source colour is compared against every candidate; distant colours are penalised.
5. The closest item wins. Whichever fuseable item sits nearest to the blended essence becomes the output, and its bias value shifts how easily it is reached.
6. Output count = total energy ÷ output energy, capped at the item's stack size and at least 1.

Formulas here are the cheapest two-stack combination found across the public item set, ranked by ingredient tier, then total stack count, then output yield. Items marked Unsolved are fuseable but no stable two-stack pair reaches them; they need three or more sources.