For Isaac, the divide between sanity and madness grows tenuously thin; a ceaseless delirium ever closer. Can you guide your characters to overcome that most intangible of adversaries, even as the lines between past, present, and future blur? After all, the hardest enemy of all is your own mind…
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Setup
Game Modes
FAQ
Challenge Cards
Credits
Setup
Card(s) Needed
Goal
The challenge is won when Unrelenting Delirium dies.
Setup
- Choose a difficulty level for the challenge:
Normal
Hard
Ultra Hard - Set up as normal for solitaire/co-op mode.
- Place Unrelenting Delirium face up to one side of the monster slots in a final boss slot.
(feel free to use your regular Delirium card as a stand-in to represent this!)
Global Modifiers
Echoes of the Past 
Bosses you attack have the abilities of each soul controlled by each player while being attacked.
Echoes of the Past 
Monsters you attack have the abilities of each soul controlled by each player while being attacked.
Echoes of the Past
Monsters you attack have the abilities of each soul controlled by each player and each monster in a minion slot while being attacked.
Tormenting Consequence
Each time a non-boss monster in a monster slot dies, put it in a minion slot.
In Your Head
Minions can’t be attacked.
Other Rules
Abilities on monster cards don’t function while they are in minion slots in this challenge (but they still exist to be copied by Unrelenting Delirium and potentially other bosses or monsters during the challenge!).
Remember that the specific rules and global modifiers for this challenge are used in addition to the general challenge rules that apply to all challenges. The general challenge rules can be downloaded separately from maestromedia.com.
Game Modes
Normal 
Unrelenting Delirium has the abilities of each soul controlled by each player and each monster in a minion slot while being attacked.
While all players control less than 6 souls, attacks can’t be declared on Unrelenting Delirium.
Hard 
Unrelenting Delirium has the abilities of each soul controlled by each player and each monster in a minion slot while being attacked.
While all players control less than 8 souls, attacks can’t be declared on Unrelenting Delirium.
Ultra Hard 
Unrelenting Delirium has the abilities of each soul controlled by each player and each monster in a minion slot while being attacked.
While all players control less than 10 souls, attacks can’t be declared on Unrelenting Delirium.
Competitive Variant 
This challenge is primarily designed for solo and co-op mode, but you can also play a game of regular competitive Four Souls with an added twist.
Setup as normal for a competitive game. Place Unrelenting Delirium face up to one side of the monster slots in a final boss slot (use the competitive variant version of Unrelenting Delirium).
Unrelenting Delirium has the abilities of each soul the active player controls and each monster in the active player’s delirium slots (see below). Non-boss monsters that die get put in these delirium slots rather than in minion slots. Unrelenting Delirium also only looks at the number of souls the active player controls, rather than all players, when determining if an attack can be declared against it (the active player needs at least 3 souls).
Delirium Slots are a new type of slot specific to this challenge. Like minion slots, delirium slots are temporary and are not refilled when empty. Unlike minion slots, each player has their own personal delirium slots, and monsters in delirium slots can’t be attacked. Abilities on monster cards don’t function while they are in delirium slots (but they still exist to be copied by Unrelenting Delirium and potentially other bosses or monsters during the challenge!).
FAQ
What happens if Unrelenting Delirium gains an ability that would cause it to leave the final boss slot?
Monsters in a final boss slot can’t leave that slot unless they die. From the general challenge rules: “A monster in a final boss slot can’t be covered and also can’t leave the slot for any reason unless it is killed (unless otherwise specified).”
Unrelenting Delirium/a monster now has multiple abilities that are triggered by the same thing, what happens?
If multiple triggered abilities controlled by the game, such as those on monsters, are triggered at the same time, the active player determines the order that they are put on the stack.
Challenge Cards
Credits
| Creator of Four Souls | Edmund McMillen |
| Challenge Design | Charlie Gill |
| Challenge Art | orisghost |
| Producer | Dustin Wessel |
| Editors | egghorse, Cody Underwood |
| Rules Advisor | Sevenut |
| Official TTS Table | Jeremy Silliman, maths |
| Playtesting TTS Table | Troy Thompson |
Information on this page is transcribed from the official PDF file with minor edits to grammar for clarity.