Kidney Stone

Kidney Stone is an unlockable passive item added in The Binding of Isaac: Afterbirth.

Effects

 * -0.2 speed and maximum speed.
 * -17 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 does 5 times Isaac's damage and pierces enemies, followed by a rapid, inaccurate spray of tears.
 * 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 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.

Synergies

 * : The temporary tears up from the kidney stone burst becomes a permanent x6 fire rate multiplier, making it one of the best items for Rock Bottom.

Interactions

 * //: Only fires one stone.
 * : The stone will not hover and will travel regardless.
 * /: Overrides Kidney Stone. Speed and range downs still apply.
 * : When Kidney Stone activates, it fires one kidney stone and then no more tears until tears stat is under a certain value (unknown).
 * : Overrides Kidney Stone. The range down is especially harmful with Dr. Fetus, making self-damage very likely.
 * : Overrides Kidney Stone.
 * //: The stone cannot split into smaller stones.
 * The Forgotten: The Forgotten will swing his club rapidly instead of shooting the burst of tears (The Forgotten still fires the stone normally).
 * : Overridden by Haemolacria. Only stat changes apply.
 * : The stone will only spawn sparks when hitting enemies.
 * : The harsh speed and range down make Libra a large stats down. Stats are increased during the barrage.
 * : Overrides Kidney Stone.
 * : The stone will not grow bigger as it travels, but it will increase in damage.
 * : 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.
 * : Number One's range down overrides Kidney Stone, for an additional -0.62. The stone is not affected by the range decrease.
 * : Overrides Kidney Stone.
 * : Overrides Kidney Stone.
 * Fires the stone like normal, followed by a barrage of Technology lasers.
 * : Overrides Kidney Stone.
 * Synergiezes now, behaving pretty buggy however (look into "bugs" down below).

Trivia

 * "Matt" refers to Matt Kap, a pixel artist for The Binding of Isaac: Rebirth, who has once been afflicted with a kidney stone.

Seeds
ZX84 DLBX (First floor Treasure Room)