Damocles

Damocles is an activated item added in The Binding of Isaac: Repentance.

Effects

 * Upon use, summons a sword that hangs directly above Isaac. As long as the sword hangs above Isaac, all item pedestals and items spawned from Machines and Beggars are doubled, spawning an additional, free item next to them.
 * The extra item spawned will be pulled from the current room's item pool.
 * Mega Chests will also spawn an extra item if they contained items.
 * After Isaac gets hit once with the item activated, at any time without warning, the sword may fall, instantly killing Isaac regardless of his health. The sword has a 1/10000 chance every 4 frames to fall.
 * Self-damage (such as from a Blood Bank, Devil Beggar, Curse/Sacrifice room, or self-damage Active Items) does not count as damage taken for Damocles, and will not give it the chance to fall.

Interactions

 * : Can invoke the effect of Damocles, which will apply permanently.
 * : Getting stabbed by Blood Oath does not trigger the chance of falling.
 * : Blowing yourself up does trigger the chance of falling.
 * : Taking damage still allows it to fall, and the sword will still kill Isaac if it falls.
 * //: The sword does not get rerolled.
 * : The sword cannot be removed from Isaac's inventory.
 * : The sword does not get removed going to the unique Bedroom. It will then cause all the options to generate 3 additional items that can be taken for free, effectively quadrupling Isaac's items. Bonus active items can spawn on top of each other, making items next to them unobtainable.
 * Butter!: Using active item will drop it and spawns an extra item pedestal on the ground; Getting hit may cause Isaac to drop the sword, removing the effect and chance of falling.
 * : Damocles does not count toward his passive item count, and cannot be removed.
 * : The sword will only gain the chance to fall if the brother who used it takes damage.
 * : The character that used Damocles must be active for double items to spawn.
 * In the case of Boss Rooms, the character that did not use Damocles must fight the boss for it to drop double items.
 * : The sword will hang over Tainted Forgotten's body but will still kill the character despite being invincible.
 * Panic Button: Does not activate when the sword falls on Isaac.
 * : Does not protect Isaac from death when the sword falls.
 * : The sword will not be removed from Isaac's inventory.

Synergies

 * / /  / other items that give shield: Nullifies the insta-kill of Damocles if the shield is active when the sword falls.
 * /: An extra item is spawned per each item cloned.
 * : If in the form of the statue, the player will be immune to the falling sword.
 * 's statue form can also save the player, but the statue transformation time lining up with the sword falling is unlikely.
 * //Wooden Cross/: Damage blocked by the shield doesn't count as damage taken. It will not, however, protect Isaac from the falling sword.
 * ///: Blocked damage does not count as damage and can delay the triggering of Damocles.
 * /: Any damage the Lost would take is likely to kill him instantly, meaning that the item's downside is greatly mitigated. Dying and respawning, however, will still trigger the chance of falling,
 * : Spawns 2 items on every use instead of 1.
 * / / other items that give invulnerability: If active, will negate the sword's fall killing Isaac.
 * When in the shadow state, Isaac can survive the insta-kill of Damocles, however this requires precise timing and can be impossible if Dark Art's charge is empty as the sword is falling.
 * If the character that used Damocles takes damage, swapping to the other character will cause the game to 'forget' that he took damage when you change back into him, making this item much safer than usual to use.

Survival
Given the 1/10000 chance for the sword to fall every 4 frames (0.133 seconds), Isaac has a ~4.4% chance to die for every minute of gameplay that passes after he takes damage with Damocles active. The following is a table for times Isaac could survive to after getting hit, along with the chances of reaching them:

Trivia

 * The item's appearance and effects are a reference to [the] Sword of Damocles, a story in which Damocles is offered to switch places with Dionysius on the throne for a day and have a taste of his power. Damocles accepts, only to find that Dionysius had a sword hanging over his throne by a single horse hair, causing him to beg to be exempted from the very fortune he accepted.
 * The Damocles can be seen hanging over Isaac's head on the Antibirth album cover.
 * There are actually two different Damocles items in the game: one (item ID 577) is the active item that the player can encounter, and the other (item ID 656) is a hidden passive item that is given when the active Damocles is used and that carries out the item's effects. The passive Damocles cannot be encountered through any normal means, even via or, nor does it appear in the collection grid. If spawned on a pedestal via the Debug Console, collecting the passive Damocles will immediately put the sword above Isaac's head as if the active Damocles were used.
 * In Antibirth, the more time player would get hit, the higher chance of Damocles falling on Isaac's head was.