Hidden Attributes

Tear Falling Speed[]

Tear falling speed is a hidden attribute that determines how far above the ground tears travel after traveling for a short period of time, and in practice increases effective range. Very high tear falling speed makes Isaac's tears arc upward then continue along "cruising altitude" so high they can cross over obstacles as if they were spectral, but they won't go through the room walls. Once the tears fall down, they will start hitting obstacles again. This compounds with the height from the tear height stat.

Items no longer give tear falling speed directly, instead tear falling speed is dynamically generated based on the range stat, shot speed stat, and tear height stat, in order to match the range stat in tiles.

Items that Affect Tear Falling Speed[]

Passive Items[]

Name	ID	Quote	Description	Quality
Blood Clot	5.100.254	DMG + range up	Tears fired from the left eye have +1 flat damage, +5 range, and +0.5 tear falling speed. Tears fired from the left eye have +1 flat damage and +2.75 range.	2
Dead Onion	5.100.336	Toxic aura tears	Grants piercing and spectral tears. Increases tear size (without increasing damage) while greatly reducing range and shot speed.	2
Godhead	5.100.331	God tears	Grants homing tears with a damaging halo. +0.5 Damage, -0.3 Tears -0.3 Shot Speed, +0.8 Tear Falling Speed, and +1.2 Range. Grants homing tears with a damaging halo. +0.5 Damage, -0.3 Tears, and -0.3 Shot Speed.	4
Ipecac	5.100.149	Explosive shots	Replaces tears with explosive and poisoning projectiles fired in an arc from the mouth.	4
Jesus Juice	5.100.197	Damage + range up	+0.5 damage, +0.25 range, +0.5 tear falling speed. +0.5 damage, +1.5 range.	2
Magic Mushroom	5.100.12	All stats up!	Makes Isaac bigger. Adds one Red Heart Container, +0.3 Damage, x1.5 damage multiplier, +5.25 Range, +0.3 Speed, and restores all Health. Makes Isaac bigger. Adds one Red Heart Container, +0.3 Damage, x1.5 damage multiplier, +2.5 Range, +0.3 Speed, and restores all Health.	4
Mini Mush	5.100.71	Speed + range up	Decreases Isaac's size, making him less likely to be hit. +0.3 speed, +1.5 tear falling speed, -4.25 range (effective range is increased). +0.3 speed, +2.5 range.	2
Mom's Contacts	5.100.110	Freeze effect	Adds a chance to shoot petrifying tears, which stop enemies in place and prevent them from moving or attacking. +0.25 range. +1.5 range.	3
Mom's Heels	5.100.30	Range up	+5.25 range, +0.5 tear falling speed. +2.5 range, enemies that touch Isaac take 12 damage.	1
Mom's Lipstick	5.100.31	Range up	+5.25 range, +0.5 tear falling speed. +3.75 range. Spawns a Heart on pickup.	1
Mom's Underwear	5.100.29	Range up	+5.25 range, +0.5 tear falling speed. +2.5 range. Spawns 3-6 Blue Flies on pickup.	1
My Reflection	5.100.5	Boomerang tears + DMG up + luck down	Gives Isaac's tears a boomerang effect. +1.5 range, +1 tear falling speed, x1.6 shot speed multiplier. 2x + 1.5 range, +1.5 damage, -1 luck, 1.6x shot speed multiplier.	2
Number One	5.100.6	Tears up + range down	Grants +1.5 tears, but severely reduces range.	2
Odd Mushroom	5.100.121	HP + DMG up, speed down	Grants one empty Heart container, +0.3 damage, +0.25 range, +0.5 tear falling speed, and -0.1 speed. Grants one full Heart container, +1 damage, +1.5 range, and -0.2 speed	2
Roid Rage	5.100.14	Speed and range up	+0.6 speed, +5.25 range, +0.5 tear falling speed. +0.3 speed, +2.5 range	2
Sacred Heart	5.100.182	Homing shots + DMG up	Adds a Red Heart Container. Grants homing tears, a x2.3 Damage multiplier, +1 flat Damage, -0.4 Tears, -0.25 Shot Speed, and +4.125 Range. Adds a Red Heart Container. Grants homing tears, a x2.3 Damage multiplier, +1 flat Damage, -0.4 Tears, and -0.25 Shot Speed.	4
Safety Pin	5.100.339	Evil + range + shot speed up	Grants one Black Heart, +5.25 range, +0.5 tear falling speed, +0.16 shot speed. Grants one Black Heart, +2.5 range, +0.16 shot speed.	1
SMB Super Fan	5.100.189	All stats up	+1 Red Heart container, +0.3 damage, +0.2 tears, +0.2 speed, +0.5 range, +1 tear falling speed. Fully restores all red hearts. +1 Red Heart container, +0.3 damage, +0.2 tears, +0.2 speed, +2.5 range. Fully restores all red hearts.	3
Synthoil	5.100.345	DMG + range up	+1 damage, +5.25 range, +0.5 tear falling speed. +1 damage, +2.5 range.	3
The Halo	5.100.101	All stats up	Grants one full Red Heart container, +0.3 damage, +0.2 tears, +0.25 range, +0.3 speed, and +0.5 tear falling speed. Grants one full Red Heart container, +0.3 damage, +0.2 tears, +1.5 range, and +0.3 speed. Heals 1 additional Red Heart.	3
Tiny Planet	5.100.233	Orbiting tears + range up	Massively increases Range and grants spectral tears. Tears orbit around Isaac at a fixed distance until they hit the ground.	0
Continuum	5.100.369	Transcendent tears	Grants spectral tears and increases range. Tears travel through walls and appear at the opposite side of the room.	2
Crown Of Light	5.100.415	The untainted gain power	+2 Soul Hearts. While Isaac has no empty red hearts, grants 2x damage, increased range, and -0.3 shot speed. Regardless of health, the crown deactivates for the current room when Isaac takes damage.	4
Kidney Stone	5.100.440	Matt's kidney stone	Isaac is occasionally forced to stop firing and charge an attack that launches a massive piercing, spectral kidney stone and a barrage of tears. -0.2 speed, decreases range.	2
Marked	5.100.394	Directed tears	Isaac will automatically fire tears directed at a red target on the ground. The target can be moved with tear controls. +0.7 tears, increases range.	0
Mom's Pearls	5.100.355	Range + luck up	+1.25 range, +0.5 tear falling speed, +1 luck. +2.5 range, +1 luck. Grants one Soul Heart.	2
Mr. Dolly	5.100.370	Range + tears up	+0.7 tears, +5.25 range, +0.5 tear falling speed, Spawns a combination of 3 Red Hearts, Soul Hearts or Black Hearts on the floor when picked up. +0.7 tears, +2.5 range, spawns 3 random types of Hearts on the floor when picked up.	3
Purity	5.100.407	Aura stat boost	Boosts one of Isaac's stats depending on the color of the aura around him. The aura disappears upon taking damage and reappears with a random color upon entering a new room. Red boosts damage, blue boosts tears, yellow boosts speed, and orange boosts range.	3
Tractor Beam	5.100.397	Controlled tears	Isaac's tears are bound to a beam emitting in the direction he's firing. +0.5 Tears, +5.25 Range, +0.16 Shot Speed. +1 Fire Rate, +2.5 Range, +0.16 Shot Speed.	3
Compound Fracture	5.100.453	Bone tears!	Increases Range. Tears turn into bones, which shatter into 1-3 bone shards upon hitting an enemy or obstacle.	3
Dad's Lost Coin	5.100.455	I remember this...	+1.5 range, +1 tear falling speed. Drops a Lucky Penny. +2.5 range. Drops a Lucky Penny.	1
Dark Prince's Crown	5.100.442	Loss is power	When at exactly one Red Heart, +0.75 tears, +1.5 range, and +0.2 shot speed. When at exactly one Red Heart, +2 fire rate, +1.5 range, and +0.2 shot speed.	1
Eye of Belial	5.100.462	Possessed tears!	Grants piercing tears. After piercing one enemy, tears start homing and deal double damage.	3

Trinkets[]

Name	ID	Quote	Description
Lazy Worm	5.350.66	Pft	Decreases shot speed by 0.5. Increases range by 4.
Tape Worm	5.350.65	Floooooooooop!	Doubles Isaac's range and halves his tear falling speed. +3 range.
Dim Bulb	5.350.101	I think it's broken	Provides a boost to all stats when Isaac's active item is completely uncharged.
Ouroboros Worm	5.350.96	Foop foop!	Tears travel in a large spiral pattern and gain spectral, with a small chance to gain homing. Also adds +0.4 Tears.
Vibrant Bulb	5.350.100	It needs power	Provides a boost to all stats when Isaac's active item is fully charged.

Other[]

In co-op, Long Baby will occasionally briefly increase range, shot speed, and tear falling speed. Dark Baby will occasionally briefly increase all stats, including tear falling speed.
Azazel starts with -1 tear falling speed, though the stat does not affect his short-range Brimstone.

Tear Height[]

Tear height is a hidden attribute that determines the height that tears spawn at. Before Repentance, this was the range stat displayed in the found hud, and most items that affected range affected this stat directly. Since Repentance, most range affecting items affect the new range stat instead of tear height, and only a few items affect tear height directly. Tear height no longer majorly affects effective range.

Items that Affect Tear Height[]

Item	Tear Height Adjustment
Base tear height	23.75
Eye of the Occult	+8
Jupiter	+8
Pluto/Inner Child's revive	x0.4
Huge Growth	+30
Mega Mush	+80
Tape Worm	x2 per Tape Worm
Telepathy For Dummies/I - The Magician	x2
Number One/Kidney Stone	-18
Multidimensional Baby	x1.5
Parasitoid's egg tears	x2

Notes[]

Tear height adjustments occur in the order of the above list from top to bottom.
Tear height can not be lowered to below 5.0.
Certain items still use tear height to calculate their effective range, these include The Boomerang, C Section (only slightly), Cricket's Body, Dr. Fetus, Eraser, Flat Stone, Haemolacria, Lachryphagy's burst tears, Monstro's Lung, My Reflection, Sharp Key, and Tiny Planet (inverted, lower tear height improves range).
- As a result, items that lower tear height, even if they don't affect range, such as Pluto and Kidney Stone, can negatively affect the effective range of the above items.
- With below 10 tear height Cricket's Body's split tears will hit the ground immediately, being unable to deal damage.
Tears that pass through Multidimensional Baby and Parasitoid's egg tears don't get reduced tear falling speed, and as a result, effective range is increased.
- Tiny Planet tears' range will increase instead of decrease in these cases.

Knockback[]

Knockback is a mechanic that determines how far an entity is pushed back by a certain force.

Tear Knockback[]

This knockback comes from Tears, most notably Isaac's. The knockback force is determined by the speed and direction of the tear, which itself is determined by Isaac's movement and Shot Speed. For example, Ring Worm does not increase the knockback stat, but does affect knockback as the tear's speed hits extremes of very fast and very slow; hitting enemies with the fastest moment of its arc applies significant knockback. Damage does not affect the knockback.

Upon collision, the tear applies two separate knockbacks on the enemy. One is collision knockback which pushes the enemy away from the tear. The other one is momentum knockback which pushes the enemy toward the tear's movement direction. Since they can have directional difference, the two knockbacks can cancel each other in some rare cases.

$\text{Collision Knockback} = \frac{V_p \times K \times M_p}{10 \times M_t}$

$\text{Momentum Knockback} = \begin{cases} M_p \times \left\vert \frac{(V_p + K)}{M_p + M_t} - \frac{K}{M_t}\right\vert, & \text{if the tear is not Piercing} \\ \frac{M_p \times V_p}{M_p + M_t}, & \text{if the tear is Piercing} \end{cases}$

Where:

V_p is the tear's velocity.
K is knockback multiplier, which is 1.7 by default but is counted as 0 when the knockback multiplier is not active.
M_p is the tear's mass, which is 8 by default.
M_t is the enemy's mass.

Knockbacks from laser is:

$\text{Laser Knockback} = \begin{cases} 1.8 \times \frac{M_p}{M_t}, & \text{if the knockback multiplier is not active} \\ 3.6 \times \frac{M_p}{M_t}, & \text{if the knockback multiplier is active} \end{cases}$

The knockback multiplier does not affect lasers' knockback.

Knockback items affect the knockback in many ways, by activating the knockback multiplier, increasing the knockback multiplier, and/or increasing the tear mass. Effects that increase the knockback multiplier do not stack, and only the highest increase applies. Effects that increase the tear mass do not stack. Soy Milk or Almond Milk decrease the tear mass, thus weakening the knockback.

Items that Affect Tear Knockback[]

Passive Items[]

Name	ID	Quote	Description	Quality
Pisces	5.100.309	Tears up + knock-back shots	-1 Tear Delay, adds knock-back shots and increases tear size. +0.5 Fire Rate, adds knock-back shots and increases tear size.	2
Soy Milk	5.100.330	DMG down + tears way up	Tears are smaller and do much less damage, but fire in very rapid succession.	2
8 Inch Nails	5.100.359	Stick it to 'em!	+1.5 damage. Replaces Isaac's tears with nails, which have increased knockback.	3
Almond Milk	5.100.561	DMG down + tears up + you feel nutty	Quadruples fire rate, with ×0.3 damage multiplier. Each tear is given a random effect that alters its movement.	1
Terra	5.100.592	Born to rock	+1 Damage. Replaces tears with rocks that deal variable damage, have increased knockback, and can destroy obstacles.	3

Trinkets[]

Name	ID	Icon	Quote	Description
Blister	5.350.77		Bounce back!	Increases knockback of tears.

Notes[]

Directional knockback affects most enemies, including bosses (except for stationary ones like Pin or Round Worm). Items (both trinkets and pickups) cannot be moved by tears, except for live bombs.
Knockback from tears provides minor crowd control for homing enemies like flies or Gapers, increasing the time it takes them to reach Isaac.
Be wary of the natural knockback from tears when trying to dodge charging enemies (like the smaller twin of Gemini, Gurglings, and Leeches): The tears can push them off-track and towards the direction you are planning to escape to.

Knockback from other sources[]

Various sources also can cause knockback. This knockback is often a little shockwave that's emitted at a certain radius in all directions, most prominently from explosives, like Bombs. Certain farts also create a knockback. Some enemies, like the Fatty, can fart, and Isaac can also do so with certain items.

Pickups (including chests) are affected by this knockback; items, however, are not.

Knockbacks from Belly Jelly, Butter Bean, Divine Intervention, Hemoptysis, and Knockout Drops are strong knockback. They do not decrease from the enemy's friction and linger for a relatively long time once applied. Any enemy affected by it takes 10 + 2 × (floor - 1) damage upon being pushed into walls or obstacles. No other knockback can deal such damage however strong it is.

Items that Cause Knockback[]

Activated Items[]

Name	ID	Quote	Description
Butter Bean	5.100.294	Reusable knock-back	Isaac farts and knocks back nearby enemies and projectiles. Enemies pushed into walls or obstacles take 12 damage.
The Bean	5.100.111	Toot on command	Isaac farts, poisoning any enemy in close range.
The Poop	5.100.36	Plop!	Spawns a pile of Poop where Isaac is standing and knocks back nearby enemies. May yield pickups like regular poop.

Passive Items[]

Name	ID	Quote	Description	Quality
Isaac's Heart	5.100.276	Protect it	Isaac himself is now immune to all damage, and a heart familiar follows him. If the heart is hurt, Isaac is hurt. The heart charges up as Isaac shoots, firing 8 blood shots, knocking back enemies, and leaving a puddle of creep when released.	0
The Black Bean	5.100.180	Toot on touch	When taking damage, Isaac farts, poisoning enemies in range. When taking damage, Isaac farts five times, poisoning and knocking back nearby enemies and leaving lingering poison clouds.	0
Farting Baby	5.100.404	He farts!	Spawns a familiar that follows Isaac and blocks enemy shots. If a shot hits Farting Baby, it has a chance to fart, which charms, poisons, or knocks back nearby enemies.	1
Belly Jelly	5.100.690	Bounce away!	Causes enemies to bounce off of Isaac, dealing damage to them if they hit an enemy or obstacle. Also gives Isaac the chance to deflect enemy shots.	3
Hemoptysis	5.100.726	Double tap sneeze	Double-tapping a fire button causes Isaac to sneeze blood, dealing damage to enemies in front of him. Affected enemies are cursed and take more damage from Brimstone-like attacks.	1
Knockout Drops	5.100.637	They pack a punch!	Adds a chance to shoot a fist tear that has extremely high knockback and confuses enemies.	2

Trinkets[]

Name	ID	Icon	Quote	Description
Butt Penny	5.350.24		Wealth of gas	Isaac will fart when he picks up a coin. Coins have a higher chance to drop from Poops.
Mysterious Candy	5.350.25		Uh-oh!	Isaac farts or poops at random intervals. Getting hit can also trigger the effect.

Notes[]

There is also a mechanic that acts as an opposite of sorts to circular knockback: a gravitational pull that is emitted from Gaping Maws, Mega Fatty (while charging up its "Vomit Storm" attack), purple champion monsters, Strange Attractor, and Suction Pitfalls.

The Binding of Isaac: Rebirth