Kidney Stone

Treasure Room Treasure Room   (page 4, column 15, line 4)   Complete challenge #29 ( The unlock is bugged and actually unlocks Blank Rune) Kidney Stone

Kidney Stone is an unlockable passive item added in Afterbirth.

Effects

• -0.2 Speed
• -15 Range
• +2.0 Tear height.
  • The increased tear height and decreased range results in overall slightly less firing distance.
• Occasionally, firing tears will cause Isaac to charge an attack with his head pulsating with a red color. After the attack has charged up, the fire button can be released to fire a kidney stone that deals extra damage while piercing enemies and walls, and to fire a barrage of tears afterwards.
  • This effect occurs approximately every 25 seconds.
  • Isaac won't be able to fire tears normally until the kidney stone has been fired.
  • The kidney stone has approximately twice the range of normal tears.
  • The tears fired afterwards are a bit inaccurate and can be fired slightly to either side.
  • The barrage will continue for its full length between Rooms, as will the state of charging the attack instead of firing tears.
• When Isaac has half a heart left, the urine that appears underneath Isaac upon entering rooms will be changed to red.

Strategy

• Activating this item before entering a difficult room, like a boss room, can allow you to deal a lot of damage right away. To do this, simply hold the attack button until you stop shooting tears.

Notes

• Tints tears red. This is only a cosmetic change.
• Incubus

  A demonic familiar that follows Isaac and shoots tears identical to Isaac's in terms of damage, range, fire rate, and effects.

  will still fire tears normally while retaining the barrage effect, making this a good item for Lilith.
  • The barrage from the Incubus will be in a straight line instead of an inaccurate burst.
  • The kidney stone itself will come out of Lilith, not the Incubus follower, even though she cannot fire tears. The barrage of tears will still only come from the Incubus.

Interactions

• Anti-Gravity

  -2 Tear Delay. Tears float in position until firing ceases, after which they will fly off in the direction they were shot in.

  : When the Kidney Stone effect is activated, the tear barrage will hover until released. The stone will not hover and will travel regardless.
• Brimstone

  Tears are replaced by a laser beam that pierces through all enemies and obstacles in its path and deals high damage. Can only be fired after a short charge-up period.

  : No effect. Speed down still applies. Range down applies to Azazel's Brimstone, making it difficult to use at base range.
• Dr. Fetus

  Tears are replaced by bombs that benefit from bomb-enhancing effects and slide a fixed range after being fired.

  : Not recommended. Bombs have very low range, making self damage very likely.
• Epic Fetus

  Isaac's tears are replaced with guided missiles, like those used by the Doctor's Remote.

  : Overrides Kidney Stone.
• The Forgotten: When in skeletal form, the Forgotten will fire the stone and swing his club rapidly instead of shooting.
• Haemolacria

  Tears are now fired in an arc. Upon hitting the floor, an obstacle, or an enemy, they burst into many smaller tears in all directions. Increases tear delay.

  : Overridden by Haemolacria. Only stat changes apply.
• Jacob's Ladder

  Tears fire sparks of electricity in random directions upon hitting an obstacle or enemy.

  : The tear barrage will spawn sparks as normal; however, the stone will only spawn sparks when hitting enemies.
• The Ludovico Technique

  Instead of firing tears, Isaac controls one floating tear that hover over obstacles. This tear deals constant damage when held in place over an enemy.

  : Overrides Kidney Stone. Tear becomes red (cosmetic change).
• A Lump of Coal

  The more distance tears travel, the more damage they will do.

  : The stone will not change appearance or grow bigger as it travels but it will increase in damage as it travels.
• Marked

  Isaac will now fire tears automatically directed at a red target on the ground which is controlled by the player. This allows for a full 360 degree tear firing radius. Can be overridden by other tear modifiers such as Mom's Knife or Brimstone.

  : Occasionally, Isaac will stop automatically firing, and an attack key must be held to release the kidney stone and continue firing.
• Mom's Knife

  Isaac's tears are replaced by a knife that pierces enemies, can travel through obstacles, and can hurt enemies while Isaac is holding it. Holding down the fire button before firing increases its range and power.

  : Overrides Kidney Stone.
• Monstro's Lung

  Increases damage and grants a charged shot that fires multiple tears in the same fashion as Monstro.

  : Overrides Kidney Stone.
• Soy Milk

  Tears shrink and do much less damage, but fire in very rapid succession.

  : Stone will be reduced to starting tear damage and is significantly smaller.
• Technology

  Replaces tears with a piercing laser with unlimited range.

  : Overrides Kidney Stone.
• Tech X

  Tears are replaced with laser rings that pierce through enemies and deal damage to enemies within them. Can be charged to increase the size of the ring.

  : Overrides Kidney Stone.
• Tiny Planet

  Range up and makes shot tears revolve around Isaac until they drop.

  : The stone and barrage of tears that follow orbit the character.

Synergies

• 20/20

  Grants double shot.

  / The Inner Eye

  Grants triple shot but decreases tears.

  / Mutant Spider

  Grants quadruple shot but decreases tears.

  : Fires more tears in tear barrage. Only fires one stone.
• Angelic Prism

  Grants a prism orbital with a large orbital radius. Tears that pass through the prism split into four multi-colored tears.

  : The stone and tear barrage will quadruple if they pass through the prism.
• Compound Fracture

  Increases range. Tears turn into bones, which shatter into 1-3 bone shards upon hitting an enemy or obstacle.

  / Cricket's Body

  Grants -1 Tear Delay and reduces Range. When tears hit an object or deplete their range, they spawn 4 smaller tears, whose Range and Damage scale with Isaac's.

  / The Parasite

  Isaac's tears split in two when they hit something.

  : Tears in tear barrage will split when hitting obstacles or enemies. The stone will not.
• Explosivo

  Isaac's tears have a chance to stick to enemies and explode.

  : The Kidney Stone has a chance to be an exploding tear.
• Ipecac

  Replaces tears with explosive and poisoning projectiles fired in an arc from the mouth.

  : Charges and fires a barrage of Ipecac shots.
• Lachryphagy

  Isaac's tears decelerate as they travel. Upon stopping or hitting an obstacle, they burst into 8 tears in all directions. Tears can be fired into other tears to feed them, increasing their damage.

  : Fires a barrage of tears that tend to clump together into larger tears, along with a kidney stone which can also be fed and bursts.
• My Reflection

  Gives Isaac's tears a boomerang effect, and increases range and shot speed.

  : All tears in tear barrage and the stone will return to Isaac.
• Pop!

  Replaces Isaac's tears with eyeballs that can bounce off of each other. The eyeballs are not limited by range, and will instead dissipate when they stop moving or when hitting an enemy or obstacle.

  : Fires a barrage of eyeball tears, and the stone behaves like an eyeball tear.
• Technology Zero

  Connects Isaac's tears with electricity that can damage enemies.

  : Fires a barrage of tears connected via electricity. The stone will also be connected via electricity.
• Trisagion

  Tears are replaced with piercing white blasts of light.

  : Behaves exactly as expected except everything looks like beams.

Seeds

 PC  ZX84 DLBX (First floor treasure room) (Both modes)

Trivia

• This item is a reference to the kidney stone Matt Kap had removed in 2015, hence "Matt's kidney stone"
  • Matt Kap was a pixel artist on The Binding of Isaac: Rebirth and presumably Afterbirth and Afterbirth+.