Blastocyst

From Binding of Isaac: Rebirth Wiki
Jump to: navigation, search
Boss Blastocyst name.png
Boss versus screen image
Base HPStage HP
190
0
Table dividing line 1.png
Ingame Appearance
In-game appearance

Entity ID
74.0
Table dividing line 2.png
Found In
Boss
Removed in Repentance
Stage The Womb icon.pngStage Utero icon.pngStage Scarred Womb icon.png
Stage The Void icon.png
Super Secret Room Icon.png
Added in Repentance
Stage The Womb icon.pngStage Scarred Womb icon.png
Stage The Void icon.png
Super Secret Room Icon.png
Degraded Boss
Small
Stage The Basement icon.pngStage The Cellar icon.pngStage Burning Basement icon.png
Stage The Caves icon.pngStage The Catacombs icon.pngStage Flooded Caves icon.png
Stage The Depths icon.pngStage Necropolis icon.pngStage Dank Depths icon.png
Stage The Womb icon.pngStage Utero icon.pngStage Scarred Womb icon.png
Medium
Stage The Womb icon.pngStage Utero icon.pngStage Scarred Womb icon.png
Stage The Chest icon.pngStage Dark Room icon.png
Large
Stage Sheol icon.png
Stage The Chest icon.pngStage Dark Room icon.png
Table dividing line 3.png
Dropped Items
Boss Boss

Blastocyst is a boss that can appear:


The large Blastocyst has 190 HP, the medium forms have 75 HP, and the small forms have 30 HP.

Behavior[edit | edit source]

Makes medium hops towards Isaac and can perform the following attacks:

  • Hops in place and upon landing:
    • Removed in Repentance Shoots 8 projectiles in all directions.
    • Added in Repentance Sends out a burst of large disorganized projectiles in all directions.
  • Leaps off-screen and lands on Isaac's position; upon landing:
    • Removed in Repentance Shoots 12 small projectiles in all directions.
    • Added in Repentance Shoots 8 larger projectiles in all directions.
  • Once enough health is depleted, it will split into two medium versions of itself.
    • Each medium form can shoot 6 projectiles in all directions.
  • Once enough health is depleted, each medium Blastocyst splits into two small versions.
    • Each small form can shoot 4 projectiles in the cardinal directions.
  • Each of these small Blastocysts leaves an Embryo behind upon defeat.

Gallery[edit | edit source]

Notes[edit | edit source]

  • Blastocyst can be encountered in groups consisting of:
    • 1 large Blastocyst and 2 small Blastocysts.
    • 1 large Blastocyst and 6 Embryos.
    • 2 medium Blastocysts and 2 small Blastocysts.

Trivia[edit | edit source]

  • Blastocyst appeared in the original The Binding of Isaac.
  • An embryo is called a blastocyst when the differentiation of cells within a morula finally begins, usually 4–5 days after the fertilization of an embryo.
  • It is very common for the medium form of the boss to spawn as normal enemies in rooms. On even later floors like Sheol, the full boss can even spawn as a common enemy.
  • As Blastocyst divides, its positive facial expressions will become less happy, losing its smile entirely when it becomes an embryo.
  • If Blastocyst is killed on spikes, none of the smaller versions will spawn. This can also apply if a very large amount of damage is dealt very quickly to any of the phases.
    • Removed in Afterbirth † This can also happen if Blastocyst is killed while still having a debuff that actively harms it (e.g. poison, fire).
  • Upon killing Blastocyst, it seems as though, for a split second, an audio clip of someone's voice can be heard. Which can be easier to make out with music turned off.
  • Added in Afterbirth † During the DLC's release, an unfair room consisting of 8 Blastocysts with a Portal in the middle existed in all environments of Chapter 4 as a result of unintentionally placed full-sized ones rather than small ones. It was acknowledged by Edmund McMillen on Twitter and was fixed shortly after.
  • Added in Repentance Blastocyst's intro animation from the original game has been restored and it has new animations for when it divides.


Bosses Boss Monstro.png
Chapter 1
Stage The Basement icon.pngStage The Cellar icon.pngStage Burning Basement icon.png
GeminiStevenBlighted OvumDingleThe Duke of FliesFamineGurglingsThe HauntLarry Jr.MonstroPinWidowThe FallenThe Headless Horseman
DangleLittle HornRag ManTurdlings
Baby Plum
Chapter 1.5
Stage Downpour icon.pngStage Dross icon.png
Lil BlubWormwoodThe RainmakerMin-MinClogColostomiaTurdlet
Chapter 2
Stage The Caves icon.pngStage The Catacombs icon.pngStage Flooded Caves icon.png
FistulaChubC.H.A.D.Carrion QueenDark OneGurdyGurdy Jr.The HollowThe HuskMega FattyMega MawPeepPestilencePolycephalusThe WretchedThe FallenThe Headless Horseman
The ForsakenThe FrailThe Stain
Big HornRag Mega
Bumbino
Chapter 2.5
Stage Mines icon.pngStage Ashpit icon.png
Reap CreepTuff TwinsHornfelGreat GideonSingeThe ShellThe Pile
Chapter 3
Stage The Depths icon.pngStage Necropolis icon.pngStage Dank Depths icon.png
The AdversaryThe BloatThe CageThe GateMonstro IIGishLokiMask of InfamyWarThe FallenThe Headless HorsemanMom
Brownie
Sisters Vis
Reap CreepThe Pile
Chapter 3.5
Stage Mausoleum icon.pngStage Gehenna icon.png
The SirenThe HereticThe VisageThe Horny BoysMomMom's Heart
Chapter 4
Stage The Womb icon.pngStage Utero icon.pngStage Scarred Womb icon.png
BlastocystThe BloatConquestDaddy Long LegsTriachnidDeathLokiiMama GurdyMr. FredScolexTeratomaThe FallenThe Headless HorsemanMom's HeartIt Lives
Sisters VisThe Matriarch
???
???
Hush
Corpse
Stage Corpse icon.png
ChimeraThe ScourgeRotgutMother
Chapter 5
Stage Sheol icon.pngStage Cathedral icon.png
SatanIsaac
Chapter 6
Stage Dark Room icon.pngStage The Chest icon.png
???The LambMega Satan
The Void
Stage The Void icon.png
Delirium
Home
Stage Home icon.png
DogmaThe BeastUltra DeathUltra FamineUltra PestilenceUltra War
Greed Mode
Ultra Greed
Ultra Greed
Ultra Greedier
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