Binding of Isaac: Rebirth Wiki
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Stage HP is a feature of some enemies, granting them extra health the higher the stage number they're encountered in is.

Calculation[]

The formula for an enemy's total health HP is where Base HP and Stage HP are the defined HP values for the given enemy and displayed in the enemies' pages, Stage is the current stage number as defined internally by the game and min and bound are functions that take the smaller of two values or bound the middle value between the two others respectively.

In practice, this means the enemy gains Stage HP extra health for the first 4 stages, gains nothing for stage 5, and then 4/5ths of Stage HP up to stage 10 after which their health stops increasing.

Chapters map to stage numbers as follows:

Stage number Normal Mode Added in AfterbirthGreed Mode
1 Basement Basement / Cellar Cellar / Added in AfterbirthBurning Basement Burning Basement / Added in RepentanceDownpour Downpour / Dross Dross I Basement Basement
2 Basement Basement / Cellar Cellar / Added in AfterbirthBurning Basement Burning Basement / Added in RepentanceDownpour Downpour / Dross Dross II Caves Caves
3 Caves Caves / Catacombs Catacombs / Added in AfterbirthFlooded Caves Flooded Caves / Added in RepentanceMines Mines / Ashpit Ashpit I Depths Depths
4 Caves Caves / Catacombs Catacombs / Added in AfterbirthFlooded Caves Flooded Caves / Added in RepentanceMines Mines / Ashpit Ashpit II Womb Womb
5 Depths Depths / Necropolis Necropolis / Added in AfterbirthDank Depths Dank Depths / Added in RepentanceMausoleum Mausoleum / Gehenna Gehenna I Sheol Sheol
6 Depths Depths / Necropolis Necropolis / Added in AfterbirthDank Depths Dank Depths / Added in RepentanceMausoleum Mausoleum / Gehenna Gehenna II The Shop The Shop
7 Womb Womb / Utero Utero / Added in AfterbirthScarred Womb Scarred Womb / Added in RepentanceCorpse Corpse I Ultra Greed Ultra Greed
8 Womb Womb / Utero Utero / Added in AfterbirthScarred Womb Scarred Womb / Added in RepentanceCorpse Corpse II -
9 Added in Afterbirth??? ??? -
10 Cathedral Cathedral / Sheol Sheol -
11 Chest Chest / Dark Room Dark Room -
12 Added in Afterbirth †The Void The Void -
13 Added in RepentanceHome Home -

Example[]

Consider a Dip with 3 base HP and 1 stage HP.

  • Basement I, i.e. stage 1: HP = 3 + (min(4, 1) + 0.8 * bound(0, 1 - 5, 5)) * 1 = 3 + (1 + 0.8 * 0) * 1 = 4
  • Womb II, i.e. stage 8: HP = 3 + (min(4, 8) + 0.8 * bound(0, 8 - 5, 5)) * 1 = 3 + (4 + 0.8 * 3) * 1 = 9.4
  • The Void, i.e. stage 12: HP = 3 + (min(4, 12) + 0.8 * bound(0, 12 - 5, 5)) * 1 = 3 + (4 + 0.8 * 5) * 1 = 11

Monsters and Bosses that use Stage HP[]

A total of 52 Monsters and 18 Bosses use this mechanic, with the Sins counted among the latter group.

Name ID Base HP Stage HP
Baby Begotten
Baby Begotten
Added in Repentance
883.0 18 3
Baby Long Legs
Baby Long Legs
206.0 16 4
Big Corn
Big Corn
Added in Repentance
217.3 6 2
Black Bony
Black Bony
Added in Afterbirth
277.0 8 2
Black Maw
Black Maw
225.0 20 6
Blister
Blister
Added in Afterbirth †
303.0 16 8
Bloodfly
Bloodfly
Added in Repentance
61.6 6 1
Blue Gaper
Blue Gaper
Added in Afterbirth
297.0 Added in Afterbirth / Removed in Afterbirth † 30
Added in Afterbirth † 16
Added in Afterbirth † 2
Bone Fly
Bone Fly
Added in Repentance
25.4 8 3
Bony
Bony
227.0 8 2
Boom Fly
Boom Fly
25.0 8 3
Bulb
Bulb
Added in Repentance
61.5 10 2
Butt Slicker
Butt Slicker
Added in Repentance
878.0 16 3
Clickety Clack
Clickety Clack
Added in Repentance
889.0 20 3
Cloggy
Cloggy
Added in Repentance
872.0 15 2
Crazy Long Legs
Crazy Long Legs
207.0 16 4
Crispy
Crispy
Added in Afterbirth †
226.2 12 4
Dank Squirt
Dank Squirt
Added in Afterbirth
220.1 15 6
Dip
Dip
217.0 3 1
Dragon Fly
Dragon Fly
Added in Repentance
25.3.0 8 3
Dragon Fly X
Dragon Fly X
Added in Repentance
25.3.1 8 3
Drip
Drip
Added in Repentance
870.0 3 1
Drowned Boom Fly
Drowned Boom Fly
Added in Afterbirth
25.2 8 3
Dump
Dump
Added in Repentance
876.0 10 1
Dump Head
Dump Head
Added in Repentance
876.1 10 1
Eggy
Eggy
Added in Repentance
29.2 20 2
Fetal Demon
Fetal Demon
Added in Repentance
886.1 40 3
Flesh Maiden
Flesh Maiden
Added in Repentance
880.0 24 4
Fly Trap
Fly Trap
Added in Repentance
873.0 16 6
Grub
Grub
239.0 10 2.5
Gurgling
Gurgling
237.0 24 4
Hardy
Hardy
Added in Repentance
826.0 15 6
Holy Bony
Holy Bony
Added in Repentance
227.1 60 14
Holy Eye
Holy Eye
Added in Repentance
60.2 20 5
Holy Mulligan
Holy Mulligan
Added in Repentance
22.2 40 3
Leper Flesh
Leper Flesh
Added in Afterbirth †
310.1 5 1.5
Ministro
Ministro
Added in Afterbirth †
305.0 9 2
Planetoid
Planetoid
Added in Repentance
229.1 28 4
Polty
Polty
Added in Repentance
816.0 14 2.5
Portal
Portal
Added in Afterbirth †
306.0 9 5
Red Boom Fly
Red Boom Fly
25.1 8 3
Red Ghost
Red Ghost
Added in Afterbirth
285.0 Removed in Repentance 25
Added in Repentance 20
Removed in Repentance 5
Added in Repentance 4
Rotty
Rotty
226.1 16 5
Sick Boom Fly
Sick Boom Fly
Added in Repentance
25.5 8 3
Skinny
Skinny
226.0 10 4
Small Baby Long Legs
Small Baby Long Legs
206.1 12 4
Small Crazy Long Legs
Small Crazy Long Legs
207.1 12 4
Splasher
Splasher
238.0 10 2
Splurt
Splurt
Added in Repentance
871.0 15 6
Squirt
Squirt
220.0 15 6
Swarm Spider
Swarm Spider
Added in Repentance
884.0 4.5 0.2
Tainted Mulligan
Tainted Mulligan
Added in Repentance
22.3 120 8
Tainted Sucker
Tainted Sucker
Added in Repentance
61.7 14 1
Vis Fatty
Vis Fatty
Added in Repentance
886.0 40 4
Wizoob
Wizoob
219.0 Removed in Repentance 25
Added in Repentance 20
Removed in Repentance 5
Added in Repentance 4
The Headless Horseman
The Headless Horseman
82.0 160 30
The Fallen
The Fallen
81.0 60 45
Krampus
Krampus
81.1 60 45
Envy
Envy
51.0 40 7.5
Gluttony
Gluttony
49.0 60 Removed in Repentance 15
Added in Repentance 20
Greed
Greed
50.0 60 Removed in Repentance 15
Added in Repentance 20
Lust
Lust
47.0 60 Removed in Repentance 15
Added in Repentance 20
Pride
Pride
52.0 60 Removed in Repentance 15
Added in Repentance 20
Sloth
Sloth
46.0 60 Removed in Repentance 15
Added in Repentance 20
Wrath
Wrath
48.0 60 24
Super Envy
Super Envy
51.1 40 7.5
Super Gluttony
Super Gluttony
49.1 60 Removed in Repentance 15
Added in Repentance 25
Super Greed
Super Greed
50.1 60 Removed in Repentance 15
Added in Repentance 25
Super Lust
Super Lust
47.1 60 Removed in Repentance 15
Added in Repentance 25
Super Pride
Super Pride
52.1 60 Removed in Repentance 15
Added in Repentance 25
Super Sloth
Super Sloth
46.1 60 Removed in Repentance 15
Added in Repentance 25
Super Wrath
Super Wrath
48.1 60 Removed in Repentance 24
Added in Repentance 30
Ultra Pride
Ultra Pride
46.2 85 Removed in Repentance 15
Added in Repentance 25

Trivia[]

  • Added in Repentance The Monster with the lowest Stage HP (and with the lowest amount among all entities) is the Swarm Spider Swarm Spider at 0.2, while the Monster with the highest is the Holy Bony Holy Bony with a staggering 14, nearly twice the amount of 2nd place. All other Monsters have an amount between 1 and 8.
  • The Boss with the highest Stage HP (and with the highest amount among all entities) is a tie between Krampus Krampus and The Fallen The Fallen at 45. All other Bosses have an amount between 7.5 and 30.
  • The Wizoob Wizoob and Added in Afterbirth Red Ghost Red Ghost are the only entities whose Stage HP were reduced in Repentance, both from 5 to 4.


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