Mom's Knife

 

"Stab stab stab"

Item ID
5.100.114

Tear Appearance

Item Pool

			Devil Room
			Treasure Room
			Devil Room
			Treasure Room

Collection Grid

(page 2, column 1, row 2)

(page 1, column 11, row 6)

Unlock Method
Defeat Satan as Isaac

Mom's Knife is a special unlockable passive item.

Effects

• Isaac's tears are replaced by a knife that pierces enemies and can travel through obstacles. Holding down the fire button increases its range and power.
  • The knife can hurt enemies while Isaac is holding it.
  • The knife deals 2x Isaac's damage while held and 6x damage at the furthest possible point of its arc, regardless of the actual maximum range stat.
• This item belongs to the Yes Mother? set. Collecting three items from this set will transform Isaac into his mother.

Notes

• The knife can be held and fired diagonally. Firing the knife diagonally requires a frame perfect input. However, this can be done easily with a controller's analog stick or with Analog Stick.
  • The knife can be fired diagonally without requiring a perfect timing.
• The knife will not work in challenges with the blindfolded effect.
• The knife cannot be used to unlock the door to the Corpse.

Synergies

• 20/20 / Conjoined / The Inner Eye / Mutant Spider: Isaac holds only one, but shoots multiple knives at their typical spread.
• Brimstone: Firing the knife also shoots a barrage of knives that goes across the screen, with each knife doing 80% of Isaac's damage. The longer the charge, the more knives are added. This effect does not work with Azazel's default mini brimstone. The brimstone-knives do not benefit from A Lump of Coal.
• Continuum: The knife can now travel through walls and appear out of the opposite wall but will still have the boomerang effect.
• Fire Mind: Still applies burning but no longer explodes.
• Flat Stone: Knife bounces as it flies away from Isaac, each bounce splash causing Isaac's tear damage.
• The Forgotten: The knife will attach to The Forgotten's bone club, forming a scythe. Increases the size of both the melee swing and the bone throw, and allows a single melee swing to deal damage to an enemy twice instead of just once. +4 damage.
• Ghost Pepper: The flames can shoot from Isaac while holding the fire button.
• Guppy transformation: Knife hits will rarely spawn an attack fly.
• Haemolacria: Haemolacria works at the same time with Mom's Knife, with Haemolacria's fire rate resulting in longer charging.
  • Mom's Knife overrides Haemolacria.
• Homing tears: Thrown knives home in on the nearest enemy extremely aggressively. They often stick on the enemy for a while before returning for extra efficiency, but their habit of targeting what's nearest rather than the intended target may also result in extra misses.
• Ipecac: Knife turns green and poison monsters that hit it. Removes Ipecac's damage increase.
  • Also adds +4 damage.
  • Damage bonus is +2 damage and the knife explodes on contact.
• Lost Contact: The knife will block bullets, even when held (similar to Trinity Shield but has a smaller blocking area).
• The Ludovico Technique: Isaac controls a floating knife that does 2x Isaac's damage. Tears stat is ignored and damage is dealt at a rate equivalent of 5 tear delay.
  • The Ludovico Technique + any multi-shot item: Isaac controls a floating knife surrounded by additional rotating knives.
  • The Ludovico Technique + Lost Contact: Floating knife loses almost all ability to block bullets, with a tiny area around the hilt that can stop shots.
  • The Ludovico Technique + Loki's Horns: Loses Loki's Horns effect; Isaac controls only one floating knife.
  • The Ludovico Technique + Brimstone: Mom's Knife overrides Brimstone leaving only the floating knife.
• Monstro's Lung: Fires a cluster of 3-5 knives at maximum charge, each dealing 2x damage.
• Proptosis: The Knife deals double damage regardless of range.
• Strange Attractor: Enemies are pulled towards the knife. The effect is minor while not firing and much stronger while the knife is launched.
• Tammy's Head: Fires 10 knives in a circle around Isaac, dealing massive damage.
• Tech X: Both fire normally.
  • Overridden by Mom's Knife.
• Unicorn Stump and other invincibility items: Even though the knife cannot be fired, the knife will deal damage while Isaac is invincible.

Interactions

• Anti-Gravity: Only tear delay down applies.
• Apple! / Euthanasia / Tough Love: No chance of higher damage or instant kills.
• Chocolate Milk: Doesn't increase damage, but reduces Isaac's tear delay by 20%.
• Compound Fracture / Cricket's Body / The Parasite: Only stat effects, if any, apply without splitting.
• Cursed Eye: Overridden by Mom's Knife.
• Dr. Fetus: Overridden by Mom's Knife.
  • Both the knife and the bombs fire normally.
  • Overridden by Mom's Knife.
• Epic Fetus: Overridden by Epic Fetus.
  • Each explosion shoots 10 knives in a circle from the point of impact.
• Explosivo: Overridden by Mom's Knife.
• Eye of Belial: Overridden by Mom's Knife.
• Holy Light: Overridden by Mom's Knife.
  • Holy Light can trigger on both held and thrown knives.
  • Holy Light triggers only when the knife is thrown.
• Jacob's Ladder: Overridden by Mom's Knife.
  • The knife will sometimes generate sparks when hitting an enemy.
• Lachryphagy: Overridden by Mom's Knife.
• Little Horn: Overridden by Mom's Knife.
• A Lump of Coal: No effect on the knife regardless of range.
• Marked: Only tears up and range up apply.
  • The knife fires in the direction of the crosshair, charging automatically, with charging time proportionate to the distance of the crosshair from Isaac.
• Monstro's Lung: Overridden by Mom's Knife.
  • Firing a knife causes several other knives to shoot out at random directions.
• My Reflection: No effect.
• Mysterious Liquid: Overridden by Mom's Knife.
  • The Knife leaves creep trails while fired.
• Pop!: Overridden by Mom's Knife.
• Rubber Cement: Overridden by Mom's Knife.
• Technology: Overridden by Mom's Knife.
  • Both the knife and the laser fire normally.
  • Overridden by Mom's Knife.
• Tiny Planet: Knives go in a spiral around Isaac; the longer the knife is charged, the bigger the spiral. Not recommended, as this makes Mom's Knife almost impossible to aim.
• Trisagion: Overridden by Mom's Knife.
• Eye of the Occult: Stat increases/decreases apply, otherwise overridden by Mom's Knife.

Trivia

• This item is used in I RULE! (challenge #26).
• In the original Binding of Isaac, buying the item from the Devil Room cost 1 Red Heart container instead of 2.
• The description of the item is a possible reference to the sniper's dialogue in Team Fortress 2.

Gallery

• 

  A comparison between the Forgotten's bone attack with and without Mom's Knife.

Seeds

PC WMB8 QEK8 (Treasure Room adjacent to spawn)

PC 6PG9 7RK3 (Treasure Room up and to the right one room from spawn)

PC DVNV YV9Y (Treasure Room adjacent to spawn)

PC JW43 H8EK (Treasure Room adjacent to spawn)

PC 1M9E Y1G1 (Treasure Room adjacent to spawn)

PC P8SE A9JW (Treasure Room adjacent to spawn)

PS4 S63T 434W (Treasure Room adjacent to spawn)

Switch JZCL 97JE (First Golden Treasure Room)

3DS Z3SL DS3W (First floor Treasure Room)

Bugs

Bug!	The Blindfolded condition also applies to the knives fired by Tammy's Head, and prevents it from working.

Bug!	Using Mom's Knife and Marked with Haemolacria will cause it to only fire towards the center of room, using the fire buttons will barely move the Marked icon; while Mom's Knife will be unusable and locked to the right.

Mom Items

Items:

• Broken Shovel
• Broken Shovel
• Divorce Papers
• Mom's Bottle of Pills
• Mom's Box
• Mom's Bra
• Mom's Bracelet
• Mom's Coin Purse
• Mom's Contacts
• Mom's Eye
• Mom's Eyeshadow
• Mom's Heels
• Mom's Key
• Mom's Knife
• Mom's Lipstick
• Mom's Pad
• Mom's Pearls
• Mom's Perfume
• Mom's Purse
• Mom's Razor
• Mom's Shovel
• Mom's Underwear
• Mom's Wig

Trinkets:

• Mom's Lock
• Mom's Locket
• Mom's Pearl
• Mom's Toenail
• Mother's Kiss

Cards:

• Emergency Contact