Kidney Stone

Kidney Stone is an unlockable passive item added in Afterbirth.

Effect

 * -0.2 Speed Down.
 * -15 Range Down.
 * +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 hue.
 * This effect occurs approximately every 25 seconds.
 * 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. The stone also has excellent range.
 * Isaac won't be able to fire tears normally until the kidney stone has been fired.
 * The tears fired afterwards are a bit inaccurate and can be fired slightly to either side.
 * 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

 * Brimstone: No effect. Speed down still applies. Range down applies to Azazel's Brimstone, making it difficult to use at base range.
 * Explosivo: The Kidney Stone has a chance to be an exploding tear.
 * Ipecac: Charges and fires a barrage of Ipecac shots.
 * The Ludovico Technique: Overrides Kidney Stone. Tear becomes red (cosmetic change).
 * Marked: Occasionally, Isaac will stop automatically firing, and an attack key must be held to release the kidney stone and continue firing.
 * Mom's Knife: Overrides Kidney Stone.
 * Monstro's Lung: Overrides Kidney Stone

Seeds
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"