Binding of Isaac: Rebirth Wiki

(in Afterbirth † and Repentance)

Parasitoid is a passive item added in The Binding of Isaac: Afterbirth †.

Effects[ | ]

  • Adds a chance to fire an egg sack which spawns slowing creep. If an egg sack hits an enemy, one to two Blue Flies or Blue Spider is spawned.
  • Egg sack tears have (except in Repentance) x2 range/(in Repentance) x2 tear height (which also increases effective range).
  • (in Repentance) This item belongs to the BeelzebubBeelzebub set. Collecting three items from this set will transform Isaac into a giant humanoid fly.
  • (in Repentance) This item belongs to the Spider BabySpider Baby set. Collecting three items from this set will transform Isaac into a humanoid spider.

Notes[ | ]

  • The chance to shoot egg sacs depends on the luck stat and is based on this formula:
    • At base luck (0), the chance is 14.29%, maxing out at 50% at 5 luck.
  • Egg sacks will also spawn blue flies or spiders if they hit Fire PlaceFire Places or invincible enemies like Death's HeadDeath's Head and StoneyStoney.
  • It is possible to create a large number of Spiders and Flies by repeatedly shooting a closed HostHost.

Synergies[ | ]

  • (in Repentance)Collectible C Section iconC Section: Parasitoid fetuses spawn spiders/flies and slowing creep with every hit on an enemy.
  • Collectible Compound Fracture iconCompound Fracture / Collectible Cricket's Body iconCricket's Body / Collectible The Parasite iconThe Parasite: When egg sacks are fired, they will split into smaller egg sacks. Split egg sacks from The Parasite will not look like egg sacks.
  • Collectible Cupid's Arrow iconCupid's Arrow: Egg sacks will apply their effect to every enemy hit.
  • Collectible Fire Mind iconFire Mind / Collectible Explosivo iconExplosivo : If the explosion effect triggers on an egg sack, it will produce a much larger pool of slowing creep.
  • Collectible Hive Mind iconHive Mind: Flies and spiders are bigger and deal double damage.

Interactions[ | ]

Overrides Parasitoid:

Other interactions:

  • (in Repentance)Collectible Dr. Fetus iconDr. Fetus: Bomb explosions have a chance of leaving the slowing creep in a larger pool than egg sack tears, however the egg sack bombs can't spawn Blue Flies/Blue Spiders.
  • Fish TailFish Tail: The duplicated flies will spawn on top of the enemy and deal damage immediately.
  • Collectible Haemolacria iconHaemolacria: Tears retain Haemolacria appearance and only the main tear can spawn flies or spiders when damaging enemies.
  • Collectible Ipecac iconIpecac: Only extra range applies on egg sack tears and they will not spawn flies or spiders.
  • (in Repentance)Collectible Montezuma's Revenge iconMontezuma's Revenge/Collectible Revelation iconRevelation: No effect.
  • (in Repentance)Collectible Spirit Sword iconSpirit Sword: The sword projectiles can still spawn flies and spiders, but the swings themselves won't.
  • Collectible Tech.5 iconTech.5/Collectible Technology 2 iconTechnology 2: Lasers are unaffected.

In-game Footage[ | ]

Trivia[ | ]

  • Parasitoid is a term for when insects' larvae live inside their hosts as a parasite before eventually killing the host.
  • (in Repentance) Parasitoid is one of the only five items that count towards 2 transformations, the other four being Collectible Skatole iconSkatole, Collectible The Bible iconThe Bible, Collectible Hive Mind iconHive Mind and Collectible Magic Mushroom iconMagic Mushroom.