Fungal Reality Shift
Fungal Reality Shifts or Fungal Shifts are a mechanic that causes certain Materials to transform (or "shift") into others, replacing them in the current run.
A Shift's replacing effect is permanent for the run, and as such, can be beneficial by eliminating dangerous materials such as Lava or Polymorphine, as well as extremely dangerous by shifting common materials like Water into hazardous materials.
Shifts are triggered by accumulating more than 180 seconds in the duration of the 
Tripping status effect, by consuming Weird Fungus, Mystery Fungus, Fungus Blood, Frog Meat, or Glue. To easily trigger them anywhere, Weird Fungus can be carried anywhere in a Powder Pouch, and also multiplied by pouring the Pouch from a great enough height, causing more of it to grow.
Fungal shifting is not possible while carrying the Vampirism perk (unless timed carefully while 
Vulnerable); building up more than 180 seconds of Tripping will stop any of the audio/visual effects of tripping without any other side effects of a fungal shift like removing the status effect or eye symbols appearing. Once the status effect timer reaches below 180 seconds, the effects will return at full intensity.
Behavior
Once the tripping effect reaches Tripping balls (180s), Fungal Reality Shifts can take place, accompanied by an audio cue and one of six prominently displayed game messages. The resulting effect causes the targeted material[s] to permanently be transformed into a new target material, determined at the event of the fungal shift, and persists for the remaining duration of the run. If the chosen material turns into the same material, that shift is skipped and the next one will take its place. If the tripping effect goes under 180 seconds while the first attempt happens, no shift will take place.
After undergoing a shift, the visual effects will rapidly fade, but further shifts cannot occur for the next 5 minutes - in addition to a maximum of 20 shifts being able to occur within a single run. Shifting an affected material again is possible, should the RNG gods allow. Supernova or Syväolento don't contribute to the 20 shift limit.
Shifts apply to original materials, for example when holding a potion of Oil(transformed) that used to be water, water will be the material used for a shift if flask material is chosen. Only one material updates when a shift happens. If other materials changed into it before, those do not update. This can create broken shift chains, where a material won't update some aspects of itself such as texture, physical attributes, or material damage. Other features such as lifetime and material reactions will still continue down the chain, but only one material further past where the chain broke. More information is in the Broken Shift Chains section below.
There is no in-game method of reversing or removing the effects of a Fungal Reality Shift, other than attempting to override the effect with more Fungal Reality Shifts. Because this change is both permanent and potentially quite hazardous [for example, all the water in your world may forever become acid, lava, polymorphine, et cetera], Fungal Shifts should be approached with caution.
Fungal Shifts will carry over into New Game Plus.
Holding a Flask
If you are holding a flask in your hand when the shift occurs, there is a 75% chance that one of the materials in the shift will be the main material in the flask, if any. If the flask material is selected to be used, one of two things will happen:
- If the material inside the flask is selected as the reactant, the shift will convert the material inside the flask and all other existing pixels of that material into a new material.
- If the material inside the flask is selected as the product, the shift will convert all existing pixels of a reactant into the material inside the flask.
Even if the material is not present in either of the tables below, it can still be chosen as either the reactant or the product material if you are holding a flask of it.
If the material in the flask was a transformed one, the original material will be used instead of the one it transformed into. This allows for a harmful shift to be overwritten with something more desirable, with enough luck.
Be careful when shifting certain materials, especially Teleportatium. Shifting Teleportatium into another material will cause all portals to the Holy Mountains to deactivate, leaving you with no method of progressing to the next area without spells that destroy matter, such as Black Hole or Luminous Drill, a teleporting spell with a Long-Distance Cast or two, or being lucky with Unstable Teleportatium
Powder pouches can also be used in the same way as flasks for fungal shifts.
Shiftable Materials
Any of the following materials can be selected, although some are more commonly selected than others. Note also that if a row with multiple materials is chosen, all of the materials in that row will be affected.
As mentioned above, holding a flask can alter which materials are selected for both initial and resulting materials.
| Probability | % Chance | Initial Material(s) |
|---|---|---|
| 1.0 | 9.319% | Water, Brine, Chilly Water, Water (Static) |
| 1.0 | 9.319% | Lava |
| 1.0 | 9.319% | Toxic Sludge, Poison, Ominous Liquid |
| 1.0 | 9.319% | Oil, Swamp, Peat |
| 1.0 | 9.319% | Blood |
| 1.0 | 9.319% | Fungus Blood, Weird Fungus, Fungal Soil |
| 1.0 | 9.319% | Freezing Liquid, Worm Blood |
| 1.0 | 9.319% | Acid |
| 0.6 | 5.592% | Diamond |
| 0.6 | 5.592% | Silver, Brass, Copper |
| 0.4 | 3.728% | Flammable Gas, Flammable Gas (Static), Poison Gas, Fungal Gas, Toxic Gas, Toxic Gas (Static) |
| 0.4 | 3.728% | Polymorphine, Unstable Polymorphine |
| 0.4 | 3.728% | Berserkium, Pheromone, Invisiblium |
| 0.2 | 1.864% | Steam, Smoke |
| 0.05 | 0.466% | Rock (Mossy) |
| 0.04 | 0.378% | Sand |
| 0.04 | 0.378% | Packed Snow |
| 0.0003 | 0.0028% | Gold (incl. gold nuggets) |
| Probability | % Chance | Result Material |
|---|---|---|
| 1.0 | 4.847% | Water |
| 1.0 | 4.847% | Lava |
| 1.0 | 4.847% | Toxic Sludge |
| 1.0 | 4.847% | Oil |
| 1.0 | 4.847% | Blood |
| 1.0 | 4.847% | Fungus Blood |
| 1.0 | 4.847% | Acid |
| 1.0 | 4.847% | Swamp (water) |
| 1.0 | 4.847% | Whiskey |
| 1.0 | 4.847% | Sima |
| 1.0 | 4.847% | Worm Blood |
| 1.0 | 4.847% | Poison |
| 1.0 | 4.847% | Vomit |
| 1.0 | 4.847% | Pea Soup |
| 1.0 | 4.847% | Weird Fungus |
| 0.80 | 3.878% | Sand |
| 0.80 | 3.878% | Diamond |
| 0.80 | 3.878% | Silver |
| 0.80 | 3.878% | Steam |
| 0.50 | 2.424% | Rock |
| 0.50 | 2.424% | Gunpowder |
| 0.50 | 2.424% | Ominous Liquid |
| 0.50 | 2.424% | Flummoxium |
| 0.20 | 0.969% | Toxic Rock |
| 0.15 | 0.727% | Teleportatium |
| 0.02 | 0.0969% | Polymorphine |
| 0.02 | 0.0969% | Chaotic Polymorphine |
| 0.01 | 0.0485% | Urine |
| 0.01 | 0.0485% | Excrement |
| 0.01 | 0.0485% | Void Liquid |
| 0.01 | 0.0485% | Cheese |
Determining the Shifted Materials
It's sometimes possible to infer which materials were shifted when the shift took place. One of the shifted materials will always be mentioned in the game message that appears [see above]. It's not deterministic whether the "reactant" or "product" material happens to be mentioned in the message,[1] but there are some pieces of information that can help:
- The material mentioned in the message given when the fungal shift occurs
- The small amounts of material that are scattered near you when the shift occurs will always be the resulting material from the shift
With this information you can determine always at least one of the materials by inspecting any newly created dregs of material around you after the shift happens - look for materials with (Transformed) in their titles or materials that emit strange, faint particles of multiple colors. If this material is the one mentioned in the shift message, the original material may be hard to determine. However, if this is not the material mentioned in the shift message, the shift message should indicate the original material that was shifted.
Additionally, if you were holding a flask for the shift, and the flask was shifted to the new material, you know without a doubt what the fungal shift was.
Inspecting Save Data
It is also possible to see the list of shifted materials by inspecting your save data. After closing the game, open your /save00/world_state.xml[2] file in a text editor. Within this file will be a section of <changed_materials> string pairs, listing each shift as a sequence of [from] -> [to] pairs. For example:
<changed_materials>
<string>
silver
</string>
<string>
magic_liquid_random_polymorph
</string>
<string>
acid
</string>
<string>
vomit
</string>
</changed_materials>
In this example, there are two separate fungal shifts: Silver -> Chaotic Polymorphine, and Acid -> Vomit.
Notably, if a converted material then becomes the target material in the new "Fungal Reality Shift", the source material in the new shift will become that converted material. E.g.
The result will be Water -> Steam
Broken Shift Chains
Order matters for fungal shifts. Consider the following chain of shifts:
- Pheromone -> Poison
- Water -> Pheromone
- Pheromone -> Ambrosia
- Poison -> Polymorphine
- Polymorphine -> Lava
- Worm Blood -> Water
Let's focus on what Water is like after these shifts. After the second shift it is still a working chain. Water converts to Pheromone, which had already converted to Poison. Effectively what happens is Water -> Poison. This is the last point where Water material updates unless another Water -> X shift happens.
The third shift overrides the first one, changing Pheromone from Poison into Ambrosia. This does not change anything for Water. Water only looked at Pheromone's "converted into" field and saw Poison. Pheromone was reduced out of the picture completely.
The fourth shift, Poison -> Polymorphine, is where Water becomes a broken shift chain. Water material will not update its "converted into" field from Poison to Polymorphine. This will be very evident from the final shift as well. When Water material is spawned in the world, it will update to have some features of Polymorphine. Water will still look like Poison and has the material damage of Poison. When ingested or stained, it will place Poison in the ingestion and stain components. Poison in these components will then act according to what they are converted into, which is Polymorphine. So Water is now a material that looks like Poison but polymorphs you and still deals the contact damage of Poison.
However, when ingested directly from a potion, the game will place Water into the ingestion component. This will not act like water, because the game looks at the "converted into" field, finds poison, and applies its effect. So ingesting from potion directly water poisons you, but ingesting from the world will polymorph you.
When a shift chain breaks, the material still gets some attributes from the shift, namely lifetime and some material reactions. If the end of the broken chain is a material with no lifetime limit, but the previous material had one, the lifetime limit stays. In this example, Polymorphine is the end of the broken chain. Polymorphine doesn't have a lifetime and Poison has no lifetime limit either, so Water stays as a stable material. It will slowly react with Toxic Sludge to create Chaotic Polymorphine. Other Polymorphine reactions also function but at a significantly slower pace.
At the very end, with all shifts listed above having taken place, Water will still look like Poison and polymorphs on contact. Polymorphine -> Lava seems like it should continue the chain, but it has no effect on Water. Only the material that breaks the chain has any effect, anything further down the chain does nothing.
The final shift, Worm Blood -> Water, will still see Poison in Water's "converted into" field and copy that. The shift reduces to Worm Blood -> Poison. This is still exactly like Water, a broken chain as described above. If it were able to look at the "converted into" field of Poison and continue down that chain, it would reduce to Worm Blood -> Lava, but this is not the case. These "converted into" fields only update when the material itself shifts.
Self Reaction Chains
Some broken chains will cause a material to react with itself when it spawns. Any reaction with only two inputs can create a chain like this, but order matters. Example chain below:
- Oil -> Water
- Water -> Molten Gold
This set of fungal shifts creates a broken chain for Oil, which reacts as Molten Gold and Water at the same time, creating Gold. In order to create these chains, you have to know which material is the first input and which is the second input in the reaction. This information is found on each material's wiki page. The example's reaction looks like this in the code:
<Reaction probability="50"
input_cell1="gold_molten" input_cell2="[water]"
output_cell1="gold" output_cell2="steam"
>
</Reaction>
The self reaction only happens if the material, Oil in this example, becomes input 2 first and input 2 is shifted to input 1 after.
Changing the color of Permanent Shield and other material-based coloring
Most particle effects are colored according to a designated material, or, if that material has been shifted, the material in its "converted into" field. By taking of advantage of this, it is possible to change the color of your Permanent Shield perk, via shifting Magical Liquid. This video explains the details and results for each material.
As some material-associated status effects normally give off particles colored based on the material the status effect is normally produced by (e.g., 
Mana regeneration is normally generated by Concentrated Mana stains or ingestion), this recoloring effect can lead to additional potentially-unexpected visual effects, particularly from broken and "twice-broken" shift chains involving these materials. For example, if shifting material A to B, B to Concentrated Mana, D to Lava, and Concentrated Mana to D, one can obtain a Mana regeneration effect with Lava-colored particles from stains from A, ingesting A from the world, ingesting B from a potion, or Kills to Mana activating. (Stains from B will yield a harmless 
On fire stain, B will set flammable materials on fire which will give harmful On fire stains, ingesting B from the world will result in a harmful 
Internal fire effect, and Concentrated Mana will act like Lava.)
Many visual effects are based on various Spark materials. Using in-potion flask reactions, it is possible to bottle Spark materials for shifting by mixing Whiskey with a little Lava to get a random "[fire]"-tagged material, which includes these spark materials, and drinking away some of the starting reactants.