Maps containing a Delirium Mirror can have the mirror walked through to unleash the rolling Delirium fog ring across the current area.
You must stay within this fog as it expands to maintain the Delirium or it will dissapear.

Defeating any monster while in this fog adds to a rewards counter, with the culminated rewards being dropped after the fog dissapears.
Simulacrum Splinters can be collected from Delirium Monsters to form a Simulacrum that allows access to a challenging Delirium encounter via the Realmgate.

Maps instilled with Liquid Emotions will have constant Delirium Fog throughout the map, and not have any rewards that drop as Delirium fog does not dissapear in these maps.

A Breach is a tear in the fabric of reality. Opening it will allow you to see and interact with monsters from another dimension.
The faster you can defeat these monsters, the longer you will keep the Breach open.

Breaches will sometimes have Clasped Hands, which drop items when walked over.
Breach Splinters can be collected from Clasped Hands and defeated Breach monsters to form a Breachstone that allows access to the Twisted Domain via the Realmgate.

An Audience with the King is an item that is an exclusive drop from the Ritual mechanic. This item allows you to access the Crux of Nothingness via the Realmgate.