Delirium

4020687075
The delirium fog won't disappear even after dying. Its permanent and I can't get my rewards.

There are 3 types of Delirium.

Normal Delirium Mirror. This one starts when you pass through the mirror and lasts for a duration (technically it travels, so you can extended or shorten the duration by moving with it or away from it), and the rewards drop when it ends. Rewards build as you progress. When you reach 3 stacks of the first tile, a 2nd tile is added. When you reach 3 stacks of the 2nd tile (and 5 of the first), a third tile is added. This is the normal Delirium encountered randomly in maps. It can be ended early using the league-specific keybind.

Permanent (or Layered) Delirium. This one is always active (no need to pass through a mirror). It occurs on maps that have had Orbs of Delirium applied to them, or that have dropped pre-orbed (the Atlas term is "with layers of delirium applied"). This one can't be ended. There is also no way to change the number of reward tiles--they do not build progressively. The number of tiles is 1 + the number of Orbs applied. So a 2-orb map ("40% delirious") will have 3 reward tiles. A reward for each tile drops whenever you fill the tile (which is done by killing mobs). So, if you have 3 currency tiles, each time you fill them, 3 currency items will drop. Note that it is entirely possible for these rewards to be hidden by your loot filter, especially if they are weaker reward types (like weapons or armour).

"Unending Nightmare" Delirium Mirror. This one only happens if you spec the Unending Nightmare node on your Atlas Passive tree. It is sort of like a blend of the two types. It is still randomly encountered in maps, but does not end, and the rewards drop as you progress.

So, if you can't end the delirium, you either have the Unending Nightmare node spec'd on your atlas tree, or it was a map with layers of delirium on it (either because you applied 1 or more delirium orbs to it or because it dropped with those layers already applied).