Delirious

Delirious is an unlockable activated item added in The Binding of Isaac: Afterbirth †.

Effect[]

Upon use, spawns Delirium in a form of a friendly boss for the current room.
Changes the appearance of the current room so it looks like a different chapter.

If multiple bosses are spawned in one room with Car Battery, The Battery, or batteries, the bosses can try to kill each other.
Sometimes bosses don't spawn because of grid entities getting in the way. When this happens the upper door appears to have friendly particles.
Unlike Mega Blast, this item can be charged with a single Lil' Battery.
- Lil' Battery gives 6 charges.
It is possible for Hush to spawn, despite Delirium not transforming into Hush during its boss battle.
If a boss summons monsters, the monsters will be charmed and will follow Isaac out of the room.
Delirious has a 60% decreased item pool weight, making it less likely to appear than other collectibles.
Certain large bosses with high health like Hush can block projectiles while Isaac stays within their hitbox, with enemies often dying when they touch the boss. Very useful for bullet heavy bosses.
Using Delirious in the Delirium fight is ill-advised as the player may confuse which Delirium is the right one, often causing more chaos in an already chaotic battle.

Book of Virtues: Generates a white wisp that resembles one random boss from this list:
- Monstro: Fires an inaccurate spray of 6-10 tears at a time, similarly to Monstro's Lung but without the charge time.
- The Duke of Flies: Each wisp will create and can have up to 3 Blue Flies out at a time, similar to Rotten Baby.
- Loki: The direction the tears are fired alternates between the cardinal and ordinal directions, similar to Loki's Horns.
- The Haunt: Fires Brimstone lasers. The laser does not need to be charged to be fired, and can tick up to 8 times for a total of 8 damage.

This item was most likely intended to be the "ultimate item" of Afterbirth †, similar to Mega Blast of the Afterbirth DLC.
- Mega Mush and Death Certificate are similar in unlocking complexity in the Repentance DLC.

PS4 T71G R34M (Starting item as Eden)

PS4 LBQ4 V4NT (Starting item as Eden; player will also start with Tech X)

PC YBCK TTZB (Starting item as Eden)

Bug!	If Delirious is used during the Delirium fight and the charmed boss is killed, it will act as if Delirium was killed, but no chest will spawn.

Bug!	If a Pink Champion Polycephalus is spawned by the item, one will have the Delirium skin and the other will have the normal Polycephalus skin.

Bug!	If Lokii is spawned by the item, one will have the Delirium skin and the other will have the normal Lokii skin.

Bug!	If a Pink Champion The Cage is spawned by the item, one will have the Delirium skin and the other will have the normal The Cage skin.

Bug!	Using Delirious multiple times rapidly in the same room can crash the game.

Bug!	Using Delirious in Boss Rush or Boss Challenge Room can close the exit even if it was finished beforehand, likely softlocking the player.

Bug!	Using Delirious can sometimes spawn a boss without its Delirium skin.

Bug!	If Delirious is used against Loki in a room layout where a Poky is present, the Poky will not deactivate until the boss and any enemies it spawns die (which may take an extremely long time). If the player has no card, pill, or rune to teleport them out of the room, this is effectively a softlock.

Bug!	Using Delirious during Mega Satan or Beast fight can lead to a softlock.

Bug!	If a Mega Fatty is spawned by the item during The Beast fight, when the Mega Fatty inhales, it will move the sprites of the bosses in the background.

Bug!	If Delirious summons Rag Mega in an uncleared room, the Purple Balls will prevent the room from clearing, effectively causing a lengthy softlock - The friendly Rag Mega does steadily lose health on his own, but this takes a fair while.