Binding of Isaac: Rebirth Wiki
Ultra   Hard
Character Isaac appearance.png
Full red heartFull red heartFull red heart
Table dividing line 1.png
Challenge Number
Starting Items
Key Piece 1 Key Piece 1
Key Piece 2 Key Piece 2
Available Rooms
Item Pool Treasure Room.png: yes          Item Pool Shop.png: yes
Boss Mega Satan portrait.png
Unlock Method

Ultra Hard Removed in Repentance Defeat ??? or The Lamb. Possession of The Polaroid The Polaroid / The Negative The Negative is required, barring getting to Dark Room Dark Room through a Sacrifice Room Sacrifice Room.
Added in Repentance Defeat Mega Satan

Added in Afterbirth †

Ultra Hard is Challenge #34. Isaac begins with both halves of the key for the Mega Satan Mega Satan battle and has to beat Mega Satan through the Dark Room.


This challenge, like the name suggests, is extremely difficult:

  • All enemies with champion forms, including bosses, will be champions.
    • Champions will not drop any collectibles.
  • The player suffers from the following curses each floor: Curse of the Labyrinth.png Curse of the Labyrinth, Curse of the Blind.png Curse of the Blind, Curse of the Lost.png Curse of the Lost, Curse of the Maze.png Curse of the Maze
    • These curses cannot be stopped through the usual methods of removing curses, such as the Rune of Dagaz Rune of Dagaz, Black Candle Black Candle or Added in RepentanceGenesis Genesis.
    • In addition to the four curses, the player may additionally suffer from either Curse of the Unknown or Curse of Darkness, which can be removed through usual means.
  • Hearts of any kind – red, soul, black, eternal, bone, golden, blended and rotten hearts – do not drop on this run.
    • Hearts can still be obtained through passive items that grant them upon collection, such as Super Bandage Super Bandage or Latch Key Latch Key.
    • Items and cards that normally drop hearts such as V - The Hierophant V - The Hierophant tarot card will not drop any hearts. Using an Ace of Hearts Ace of Hearts card will consume all pickups in the room, and not drop any hearts.
    • However, items that add hearts directly to the player's count (such as Balls of Steel or the Satanic Bible Satanic Bible) will work.
  • Every boss fight that can be, will be double trouble.
    • Since the Basement can't have double trouble bosses, these don't start until Caves Caves.
  • Only The Negative The Negative drops after killing Mom Mom.
    • This forces the player to progress through Sheol Sheol and the Dark Room Dark Room to fight Mega Satan.
      • Removed in Repentance Even though the option to proceed upward through the Cathedral Cathedral is presented, the run will end after defeating Isaac and touching the chest will not give the player credit for completing the challenge.
        • The player can also beat the challenge by defeating Delirium Delirium.
          • Some players report no victory trophy spawning after defeating Delirium, under unknown conditions. It may not be safe to attempt this route.
  • If the player manages to defeat Hush Hush, the entrances to the Removed in Repentance Cathedral Cathedral, Sheol Sheol, and The Void The Void appear.


  • Attempt to find valuable items from the two items rooms that appear in the Basement.
  • The D10 D10 can be surprisingly helpful; most of the time, it will reroll enemies into non-champion forms, and as the D10 can never reroll enemies into portals, it makes managing rooms with portals much easier.
    • Added in Repentance The D10 rerolls champion enemies into new champion enemies. Additionally, portals no longer spawn outside of The Void The Void.
  • The Glowing Hour Glass Glowing Hour Glass will allow the player to retry difficult rooms, avoid detrimental items, and peek at pills without the risk of harmful effects.
  • Trinkets that drops hearts as pickups such as Bloody Penny Bloody Penny or Monkey Paw Monkey Paw are useless in this challenge. However, those that directly heal such as Isaac's Fork Isaac's Fork or Stem Cell Stem Cell will still function.
  • PHD PHD is very valuable, as it reveals all pills, replaces detrimental pill effects with positive ones, and heals two red hearts upon pickup.
  • Hematemesis is a major problem in this challenge as it drains all your red hearts and does not give them back.
  • Removed in RepentanceItems that reroll the player such as the D4 D4 and the D100 D100 can be used to amass health very quickly, as hearts generated from items are not removed if the items that granted them are rerolled.
    • Added in RepentanceItems lost from the D4 D4 and the D100 D100 now remove associated hearts.
  • Removed in RepentanceThe Clicker Clicker can potentially transform Isaac into Keeper Keeper, allowing him to heal with coins. That said, using it will remove your most recently collected item, so it shouldn't be used if it would remove a powerful item or Key Piece 2 Key Piece 2.
  • Look for Library Library and Bedrooms. Both of these rooms contain resources that can replenish the player's health.
  • Rainbow Poop Rainbow Poops can be destroyed to fully heal the player.
  • Bombing Tinted Rocks is much less beneficial for the player, as soul hearts will not drop from them.
    • Tinted Rocks can still contain The Small Rock The Small Rock, however, so if the player has a surplus of bombs or another way to destroy rocks, there is no reason to not destroy them.
  • Deals found in Devil Room Devil Rooms are generally not worth taking. It may be preferable to pursue Angel Room Angel Rooms instead, as the player already has both key pieces, which greatly increases their chances of spawning. Due to no Soul hearts or Black hearts being able to spawn naturally, taking damage and lowering the chance for a Devil / Angel room is very common. Make sure to find items that give these hearts such as Book of Revelations Book of Revelations or Satanic Bible Satanic Bible.
    • One-heart deals are almost never beneficial — many one-heart deals do not pay for themselves, whether that be in health or other effects. Avoid taking one-heart deals unless you are confident that they are worth their cost.
    • Two-heart deals are very powerful, such as The Pact The Pact and Brimstone Brimstone. Be wary that Abaddon Abaddon can remove the player's red hearts, making items such as Pyromaniac Pyromaniac, Yum Heart Yum Heart and Placenta Placenta useless until the player regains red hearts.
      • Judas' Tongue Judas' Tongue will hide two-heart deals due to Curse of the Blind. It is therefore a bad idea to hold Judas' Tongue if the player desires to extract powerful items from a deal.
    • Added in Repentance Satanic Bible now changes the Boss Room Boss Room item into a Devil Deal, which depending on the item cost (as 2 heart deals generally provide better items), is not recommended
    • If Red Chest Red Chests spawn in the Devil Room, be wary of picking up any items that they may contain. The Red Chest item pool contains powerful items such as Dead Cat Dead Cat but also contains potentially run-ruining items such as Cursed Eye Cursed Eye and Curse of the Tower Curse of the Tower.
  • Do not enter Curse Room Curse Rooms and do not use Sacrifice Room Sacrifice Rooms.
    • Curse Rooms very rarely contain a worthwhile item, and as Curse of the Blind is in permanent effect, it is impossible to tell if an item in a Curse Room contains a good item, such as Dead Cat Dead Cat, or a bad item, such as Curse of the Tower Curse of the Tower.
    • Sacrifice Rooms do allow the player to potentially obtain a powerful Angel Room Angel Room item; however, spending at least three full hearts for a chance at getting an item is almost always not worth it, especially as hearts do not naturally drop. Additionally, there is no reason to fight the angels, as the player already has both key pieces, and there is no reason to teleport early to the Dark Room and skip multiple Treasure Rooms, as the player is forced to take The Negative The Negative anyways.
  • Removed in RepentanceThe Colorful Baby, which can be utilized in co-op mode, makes the Ultra Hard challenge trivial, as its healing effect can be used infinitely.
  • Added in RepentanceDue to the permanent Curse of the Blind and the inability for hearts to drop, Binge Eater Binge Eater is an extremely powerful item as long as you can time the item swapping properly. This removes the worry of most harmful items while supplying a lot more healing and stats, and even allowing Devil Deals to be utilized to their fullest extent. The only drawback is the fact it is from the Secret Room pool, therefore making it very hard to come across. If you have the patience to farm Secret Rooms for this item, it can essentially guarantee a win.
  • The D7 D7 will decrease the difficulty of rooms, as it does not reroll enemies into champions.
  • Added in RepentanceShard of Glass Shard of Glass is a very dangerous item in this challenge, as once damaged, there are no ways to stop the health draining effect unless you find an HP up, as heart pickups of any kind cannot spawn in Ultra Hard.



  • Despite being the "Ultra Hard" challenge, this challenge is actually played in Normal Mode. Although it is not as noticeable in Afterbirth, in Repentance, it is far easier to notice due to the lowered shot speed of many enemies.