Spirit Sword

Spirit Sword is a passive item added in The Binding of Isaac: Repentance.

Effects

 * Replaces Isaac's tears with a sword he can swing in front of him.
 * The swing does 3x Isaac's damage +3.5 and deals knockback to both enemies and Isaac if it hits.
 * The sword can be swung as rapidly as the fire button can be tapped.
 * The sword swing can collect pickups.
 * If Isaac's total health is equal to or greater than his number of Red Heart containers (same rule as regular Challenge Rooms), the sword fires a projectile when swung.
 * The projectile deals damage equal to Isaac's damage +2, and has a cooldown equal to 2x Isaac's normal tear rate.
 * Holding an attack button charges a spin attack, ready when the sword flashes, which damages all enemies around Isaac. It also deflects enemy projectiles, which can damage enemies who get hit, and launches a projectile regardless of Isaac's current health.
 * The circular swing deals 8x Isaac's damage +10, and the projectile created from it deals 4x Isaac's damage +4.
 * The charge time is based on Isaac's tears stat, at ~4x Isaac's normal tear rate.
 * While charging, the sword will damage the first enemy that contacts it. This will cancel the spin attack.

Synergies

 * //// Keeper/Conjoined Transformation: Isaac spins one additional time for each extra tear, firing extra projectiles on each spin. No effect on the normal swing.
 * : The fired projectile will burst into multiple swords.
 * : The body holds the sword while the head will only block projectiles.
 * : The fired projectile can take on Explosivo's effects. The sword swing can leave behind Explosivo tears.
 * : Random chance to swing extra swords in random directions.
 * : The fired projectile receives Godhead effects.
 * : Sword becomes huge, but smaller than with Polyphemus. The projectile is now fired in an arc and splits on collision with enemies and obstacles. Charge time is increased, but swing rate remains the same.
 * : Both the sword swing and the projectile can trigger Holy Light.
 * : The item fires normal tears and can be charged as fast as the sword can be swung. Doing a spin attack will fully charge Isaac's Tears.
 * : Random chance upon swinging to have a sword in all 4 cardinal directions. Performing a spin attack when this occurs results in a 4-way spin.
 * : Sword swings reflect projectiles.
 * : An additional ring will appear upon fully charging it. Spin is delayed by a bit.
 * : An additional sword is added to Isaac's back, and can be swung as normal.
 * : When doing the spin attack, Isaac throws the sword a short distance, which spins as it travels.
 * Mom's Knife + : A technology laser connects Isaac and the sword while it's being thrown.
 * Mom's Knife + : Launches a barrage of knives from Isaac's mouth after doing the spin attack.
 * Mom's Knife + : Full Charge launches a sword surrounded by Tech X that swings back to Isaac.
 * : The sword and fired projectile become gigantic. Charge time is increased, but swing rate remains the same. Swings will also shake the screen.
 * : The fired projectile bounces.
 * : Sword becomes a lightsaber. Surrounds Isaac with a laser on every swing. Enemy projectiles are deflected by both normal and charged attacks.
 * : Sword is additional to the laser and both can be used.
 * : The fired projectile is a Trisagion blast.
 * The fired projectiles will combine and split.

Interactions

 * : Sword beams are affected normally by Anti-Gravity. Regular sword swipes are overridden, but spin attacks freeze for a short time before firing.
 * : Sword swing has a random chance to become red and deal increased damage.
 * : Overridden by Spirit Sword.
 * : Overridden by Spirit Sword.
 * : Overridden by Spirit Sword.
 * : Overridden by Spirit Sword.
 * : The projectile can be controlled.
 * : Sword strikes and beams can burn enemies, and beams have a chance to explode.
 * : Spirit Sword will only work with The Soul, no changes to The Forgotten.
 * : Incubus tears are replaced with a sword, identical to Isaac.
 * : Sword beams are exploding shots that deal Isaac's damage — does not apply Ipecac's +40 damage modifier.
 * : Both the sword shots and sword swing create electricity.
 * : Overridden by Spirit Sword.
 * : Overridden by Spirit Sword.
 * : Overridden by Spirit Sword. Stats upgrade still applies.
 * : Overridden by Spirit Sword.
 * : Every swing sword gains a different color and effect based on that color.
 * : The sword swing has a chance to stick boogers to enemies it hits. The beam can stick to enemies.
 * : No effect.
 * : Overridden by Spirit Sword.
 * : Sword shots are connected with electricity, swings are unaffected.
 * : Only the Sword's beams can destroy rocks.
 * : No effect.

Trivia

 * The function of this item is a reference to the Master Sword in many The Legend of Zelda games.
 * This item is used in Isaac's Awakening (challenge #39).
 * When combined with Technology, the sword becomes a lightsaber, which is a reference to Star Wars.