Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki
Character Isaac appearance.png
Full red heartFull red heartFull red heart
Table dividing line 1.png
Challenge Number
Available Rooms
Item Pool Treasure Room.png: yes          Item Pool Shop.png: yes
Boss Mom's Heart.png
Gold Heart Gold Heart
Unlock Method


Added in Afterbirth

XXXXXXXXL is Challenge #21. This challenge changes all floors to be the size of XL Womb but does not combine the floors of each chapter. The goal is to defeat Mom's Heart/ It Lives. Alternatively, you can defeat The Lamb by teleporting to Dark Room Dark Room via a Sacrifice Room, or Delirium if the portal to The Void appears after defeating Mom.


Due to the floors being much bigger, it makes important rooms like Treasure Rooms and Shops take significantly longer to find, which can make the run difficult if Isaac has rather weak items. It also makes Secret and Super Secret Rooms much harder to find. Although all floors are technically XL, there is only one treasure and boss room on each floor. On the plus side, since there are more rooms, there are more opportunities to generate pickup items.


  • Items and pickups that reveal the map are very crucial, allowing easy maneuvering between Special Rooms throughout floors.
  • Items that provide benefits based on clearing rooms, like 15►Little C.H.A.D. Little C.H.A.D., will help Isaac significantly because of how many rooms he will go through in this challenge.
  • Teleportation cards, such as The Stars and The Hermit, are very valuable, as they allow easy access to Special Rooms. The Emperor is especially powerful, as it can be used to skip the entirety of a floor.
  • Avoid items that teleport Isaac at random, such as Cursed Skull Cursed Skull, as they can significantly slow down progress by potentially teleporting him to the other side of the map. Picking up the 15►Cursed Eye Cursed Eye is not recommended for the same reasons.
  • Added in Repentance Planetariums are very useful for this challenge. Added in Repentance15►Sol Sol can be used to find the boss room, Added in Repentance15►Terra Terra can break doors with ease, and Added in Repentance15►Mercurius Mercurius allows you to walk through rooms with ease. Considering you might skip an item room or two anyway in the interest of time, this can be a very effective way of completing the challenge.


  • Curse of the Labyrinth can still spawn as normal, combining the two floors as normal, and causing there to be two treasure rooms and boss rooms. The size is unchanged.


MainPageChallenges.png Challenges MainPageChallenges.png

1. Pitch Black 2. High Brow 3. Head Trauma 4. Darkness Falls 5. The Tank 6. Solar System 7. Suicide King
8. Cat Got Your Tongue 9. Demo Man 10. Cursed! 11. Glass Cannon 12. When Life Gives You Lemons 13. Beans! 14. It's in the Cards
15. Slow Roll 16. Computer Savvy 17. Waka Waka 18. The Host 19. The Family Man 20. Purist
21. XXXXXXXXL 22. SPEED! 23. Blue Bomber 24. PAY TO PLAY 25. Have a Heart 26. I RULE! 27. BRAINS!
28. PRIDE DAY! 29. Onan's Streak 30. The Guardian
Afterbirth †
31. Backasswards 32. Aprils Fool 33. Pokey Mans 34. Ultra Hard 35. Pong
36. Scat Man 37. Bloody Mary 38. Baptism by Fire 39. Isaac's Awakening 40. Seeing Double 41. Pica Run 42. Hot Potato
43. Cantripped! 44. Red Redemption 45. DELETE THIS
The Binding of Isaac: Rebirth The Binding of Isaac: Rebirth The Binding of Isaac: Rebirth
Achievements Achievements Attributes Attributes Bosses Bosses TarotCard.png Cards and Runes Challenges Challenges Chapters Chapters
Characters Characters MainPageBabies.png Co-op Items Items Item pools Item pools Monsters Monsters Objects Objects
Pickups Pickups Pills Pills Rooms Rooms Seeds Seeds Transformations Transformations Trinkets Trinkets