Binding of Isaac: Rebirth Wiki

The Host is Challenge #18, starting with the items Collectible Spiderbaby iconSpiderbaby, Collectible The Mulligan iconThe Mulligan, and the TickTick. The goal is to defeat Boss Mom ingameMom. This Challenge is unlocked by default.

Difficulty[ | ]

  • 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.

Strategy[ | ]

  • ShopShops 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 Collectible Hive Mind iconHive Mind, which will make blue flies and blue spiders bigger and stronger.
  • Isaac starts with one item each for the (in Afterbirth † and Repentance) Spider BabySpider Baby transformation and the BeelzebubBeelzebub transformation, meaning only two more items from each set will grant Isaac special abilities. While the lack of treasure rooms somewhat limits the possibility of completing either transformation, it is still possible:
    • Collectible Hive Mind iconHive Mind counts for (in Repentance) both transformations ((except 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 (except in Rebirth)Collectible Spider Mod iconSpider Mod.
    • (except in Rebirth)Collectible Sticky Bombs iconSticky Bombs from (except in Rebirth) Bomb BumBomb Bum is the only other possible item for the set that appears outside the Treasure Room pool.
    • For the Beelzebub set, the only other item in the Shop pool is (except in Rebirth)Collectible Jar of Flies iconJar of Flies, which synergizes well with Collectible Hive Mind iconHive Mind.
    • (in Repentance)Collectible Plum Flute iconPlum Flute, another Beelzebub set item, can be easily acquired by not attacking (in Repentance) Boss Baby Plum ingameBaby Plum for about 30 seconds.
    • Collectible Skatole iconSkatole, another Beelzebub set item, can be won from Shell GameShell Games, which are likely to spawn in ArcadeArcades.
    • Key MasterKey Masters have more than a dozen fly items that contribute to the Beelzebub set that they could pay out with.
    • Isaac still produces flies when firing at lowered HostHosts, so it is possible to farm flies off of them

Reward[ | ]

Trivia[ | ]

  • 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.