Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki
The   Host
Character Isaac appearance.png
Full red heartFull red heartFull red heart
Table dividing line 1.png
Challenge Number
Starting Items
15►The Mulligan The Mulligan
15►Spiderbaby Spiderbaby
Tick Tick
Available Rooms
Item Pool Treasure Room.png: no          Item Pool Shop.png: yes
Boss Mom portrait.png

The Host is Challenge #18, starting with the items 15►Spiderbaby Spiderbaby, 15►The Mulligan The Mulligan, and the Tick Tick. The goal is to defeat Mom. This Challenge is unlocked by default.


  • The lack of Item room isn't as well compensated by the starting items when compared to the other challenges. Isaac also doesn't start with an active item.


  • Shops can sell Mom's Purse, allowing a second trinket or Smelter allowing the tick to be smelted and new trinkets to be picked up.
  • Shops can also sell 15►Hive Mind Hive Mind, which will make blue flies and blue spiders bigger and stronger.
  • Isaac starts with one item each for the Spider baby transformation and the Beelzebub transformation. Meaning two more items from each set will give Isaac a marked advantage. While the lack of treasure rooms somewhat limits the possibility of completely either transformation, it is still possible:
    • The aforementioned 15►Hive Mind Hive Mind counts for Added in Repentance both transformation (Removed in Repentance just the Beelzebub transformation), and is in the shop pool.
    • The only other shop item that's in the spider baby set is Added in Afterbirth15►Spider Mod Spider Mod.
    • Added in Afterbirth15►Sticky Bombs Sticky Bombs from Bomb Bum is the only other possible item for the set, sans the treasure pool.
    • For the Beelzebub set, the only other item in the shop pool is Added in Afterbirth15►Jar of Flies Jar of Flies, which synergies well with 15►Hive Mind Hive Mind.
    • Added in Repentance15►Plum Flute Plum Flute, another Beelzebub set item, can be easily acquired by not attacking Baby Plum for about 30 seconds.
    • 15►Skatole Skatole, another Beelzebub set item, can be won from shell games, which is likely to spawn in arcades. Arcades can only spawn on even numbered or XL floors, and only when Isaac has more than 5 cents. (Having more than 2 keys means the arcades may be replaced by vaults however)
    • Key masters has more than a dozen fly items that contribute to the Beelzebub set that he could pay out with.
    • You still produce flies when firing at a lowered Hosts, so it is possible to farm flies off of them



  • A host is an organism that is infected by a parasite, which explains why Isaac has items and trinkets relating to parasites.
  • This challenge is similar to the 'Lord of the Flies' challenge in the original game.