During expeditions there is a chance of encountering Curios. There is a chance of a good or bad event from touching a Curio. Supply items can be used on curios, such as a torch or a key, to favorably alter the chances of getting a good or bad event.
Curios can be found either inside rooms or corridor segments. Different locations contain different kinds of curios, but some varieties of curio are found throughout all types of dungeon. Each room may only contain one curio, while corridor segments can contain more than one curio. Differently from obstacles, curios do not prevent passage when not activated, and it is thus possible to leave them be to minimize risk, especially if there is a lack of correct provision items to trigger their benign effects.
Once the party enters the room or segment that contains the curio, it can be clicked to activate a prompt. Through the prompt, the curio can be activated directly or with the use of a provision item: curios will react differently to certain items. Normally, the use of the correct provision item will trigger a positive effect, removing the chance of negative effects occurring, but there are exceptions. There are a few harmless curios that do not activate a prompt and are immediately searched when interacted with.
Some curios grant loot upon activation. There is a fixed pool of items that can be looted by specific curios, but additional loot due to a low light level will be calculated separately and can thus be dropped even by curios with very specific loot drops. The Antiquarian can cause special treasure to drop when she personally interacts with curios.
Many curios have effects such as stress infliction, healing, bleeding, blighting, the application of buffs and debuffs or the gain/removal of a Quirk that will affect individual heroes. The affected hero is always the one currently selected at the moment of activation. It is advisable, upon activating risky curios, to select a hero with good resistances or one that could potentially be affected by the negative effects without endangering the expedition.
Update: currently, as diseases have been reclassified as something different from a quirk, curios no longer cure diseases (i.e. Eerie Coral with Medicinal Herbs did not cure anything on a character with no quirks with the runs disease).
Heroes with certain Quirks or conditions will sometimes interact with a curio without the player necessarily prompting them to do so. This is determined via the type of Curio presented and the condition the Hero has - to i.e. a hero with the Bloodthirsty quirk may interact with a Dinner Cart or Mummified Remains. Specifically, each Curio has a number of "types" that it is associated with, which these conditions are specifically attuned to - the aforementioned Dinner Cart and Mummified Remains both having the "Body" typing (among others), which the Bloodthirsty Quirk specifically responds to.
Heroes forcibly interacting with a Curio will never use a Supply Item, resulting in the default consequences of interacting with the Curio every time regardless of whether this result is innocuous, dangerous, or even deadly. In addition, several forced interactions have the additional effect of the Hero stealing any loot that may have resulted for themselves - if this happens, the Loot is revealed but grayed out, and cannot be taken.
Some quests require the player to activate curios with special items given at the start of the quest or retrieve special items from these curios. Unlike other curios, these curios can be found in either corridors or rooms (unless otherwise mentioned).