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.

Interactions

 * : When the Kidney Stone effect is activated, the tear barrage will hover until released. The stone will not hover and will travel regardless.
 * : No effect. Speed down still applies. Range down applies to Azazel's Brimstone, making it difficult to use at base range.
 * : Not recommended. Bombs have very low range, making self damage very likely.
 * : Overrides Kidney Stone.
 * The Forgotten: When in skeletal form, the Forgotten will fire the stone and swing his club rapidly instead of shooting.
 * : Overridden by Haemolacria. Only stat changes apply.
 * : The tear barrage will spawn sparks as normal; however, the stone will only spawn sparks when hitting enemies.
 * : Overrides Kidney Stone. Tear becomes red (cosmetic change).
 * : The stone will not change appearance or grow bigger as it travels but it will increase in damage as it travels.
 * : Occasionally, Isaac will stop automatically firing, and an attack key must be held to release the kidney stone and continue firing.
 * : Overrides Kidney Stone.
 * : Overrides Kidney Stone.
 * : Stone will be reduced to starting tear damage and is significantly smaller.
 * : Overrides Kidney Stone.
 * : Overrides Kidney Stone.
 * : The stone and barrage of tears that follow orbit the character.

Synergies

 * //: Fires more tears in tear barrage. Only fires one stone.
 * : The stone and tear barrage will quadruple if they pass through the prism.
 * //: Tears in tear barrage will split when hitting obstacles or enemies. The stone will not.
 * : The Kidney Stone has a chance to be an exploding tear.
 * : Charges and fires a barrage of Ipecac shots.
 * : 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.
 * : All tears in tear barrage and the stone will return to Isaac.
 * : Fires a barrage of eyeball tears, and the stone behaves like an eyeball tear.
 * : Fires a barrage of tears connected via electricity. The stone will also be connected via electricity.
 * : Behaves exactly as expected except everything looks like beams.

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+.

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