Glowing Hour Glass

Effect

• On use, Isaac will be returned to the previous room and everything that happened in the current room will be undone.
  • Health, bombs, coins, keys, cards/runes/pills, items, and trinkets will be restored.
  • Certain consumables (such as the (Joker) Joker) do not get restored.
  • Score and Time will reset, but about one second will be spent in unskippable animation after use.
  • Completion marks earned in the room will be removed.
  • (Added in Afterbirth †) Event counters will get restored (including Donation Machines, Greed Donation Machines, and Eden's Blessing).

Notes

• (Removed in Repentance) Does not return extra lives.
• If the Glowing Hour Glass to go back in time to previous room, without moving to another room after the activation, each use will multiply some familiars that persist through rooms by duplicating them. (This is possibly a bug)
  • Familiars that can be multiplied:
    • Blood Clots from (Tainted Eve) Tainted Eve/(Added in Repentance) Sumptorium
    • Blue flies and spiders
    • (Added in Repentance) Abyss locusts
    • Friendly monsters spawned by items (i.e. (Added in Repentance) Friend Finder)
    • Mini-Isaacs spawned by (Added in Repentance) Giant Cell
    • Wisps
      • Wisps from (Added in Repentance) Vengeful Spirit act very unusual, they appear at the entrance of each room Isaac enters and shoot in the direction that Isaac currently shooting. Wisps from the (Added in Repentance) Book of Virtues that exceed the limit of 26 wisps will have this same behavior.
        • (Added in Repentance) Lemegeton wisps, however, do not retain this behavior and will still spin around Isaac even if they exceed they limit of 26 possible wisps, they also only multiply existing ones.
  • There appears to be a limit to the number of familiars that can be gained through this method.
• Using a (Joker) Joker and then the Glowing Hour Glass to return does not guarantee a Devil Room for every floor as the Joker card does not get refunded. The reason for this is that you immediately change rooms after the Joker card is used, as such reverting to before it was used is impossible.
• Does not return health lost entering or leaving a Curse Room, as the health was lost in the previous room.
• (Removed in Repentance) Does not return keys or health used to enter special rooms.
• Does not preserve the Devil Room or Angel Room door if used to return to the Boss Room.
• Does not turn a character back into another should they have been revived by Ankh, Lazarus' Rags, or Judas' Shadow.
  • (Added in Afterbirth †) Character changes are reverted by Glowing Hour Glass.
• (Added in Afterbirth †) Does not affect the chance for a portal to (The Void) The Void to spawn (the portal will not spawn if it didn't spawn initially).
  • Does not affect the chance for a Devil Room or Angel Room to spawn (it will not spawn if it didn’t initially)
• (Removed in Afterbirth †) Donations to the Donation Machine or Greed Machine are not reverted, and they can be reset into a working state once jammed.
  • Other counters not tied to your specific run, such as Slot Machines or Tinted Rocks destroyed, continue to accumulate, allowing easy unlocking of secrets such as the (Counterfeit Penny) Counterfeit Penny, the D4, and Conquest if you have access to infinite uses of the Glowing Hour Glass (see below).
• With the Curse of the Blind, Glowing Hour Glass can be used to pick up or purchase an unknown item to see what it is, then decide whether or not to undo picking it up.
• Using the Glowing Hour Glass to prevent picking the Glowing Hour Glass up while previously having had an active item will return the active item and discharge it completely.
• No Damage Achievements are still available if the Glowing Hour Glass is used to reset damage.
  • (Added in Repentance)(Perfection) Perfection is still able to drop if the Glowing Hour Glass is used to reset damage.
• (Removed in Afterbirth †) Isaac's temporary familiars (Blue Flies and Spiders) duplicate when using the Glowing Hour Glass.
  • If combined with The Battery or Sharp Plug while Blue Spiders are present, this combo can generate an infinite army of Blue Spiders.
• The Retro Vision Pill will continue to affect the game even after using the Glowing Hour Glass.
• (Removed in Repentance) Can be used to unlock multiple achievements tied to the killing of certain bosses such as Mom's Heart / It Lives.
• If there is a Lil' Battery in a Shop, the Glowing Hour Glass can be used infinitely, by entering the Shop without a charge and using the Lil' Battery to recharge and exit the shop. This is useful for duplicating temporary familiars or filling up the Donation Machine, among other uses.
• (Removed in Repentance) Using the Glowing Hour Glass right after beating Mom's Heart / It Lives / Ultra Greed allows you to get additional Eden tokens.
• (Removed in Repentance) If a new game is started and (Eden) Eden begins with this item, using it in the first room will cause the game to crash.
• Does not remove collection page entries if it undoes collecting an item for the first time.
• (Added in Repentance) Using the Glowing Hour Glass after beating Mom's Heart in (Mausoleum) Mausoleum/(Gehenna) Gehenna II will transport the player to the previous room without the Knife Pieces, but the door to Mom's Heart will also be closed. The following floor will be (Womb) Womb/(Utero) Utero/(Scarred Womb) Scarred Womb and not (Corpse) Corpse.
• (Added in Repentance) Using the Glowing Hour Glass after entering a new floor will teleport you back to the boss room of the previous floor.
• (Added in Repentance) (Bethany) Bethany's soul heart container does not get reset upon activating this item.
• (Added in Repentance) If (Tainted Jacob) Tainted Jacob is hit by Esau, using the Glowing Hour Glass will return him to normal form in the previous room.
• (Added in Repentance) The guaranteed angel room chance can be preserved if the item is used after entering the first devil room.
• (Added in Repentance) If used during The Beast fight, it will teleport Isaac to the center of the room and have no further effect.
• (Added in Repentance) May be helpful for finding Planetariums, as it lets the player effectively skip item rooms while also seeing if what's inside them is worth taking.
• (Added in Repentance) The chance of a Planetarium generating on future floors can be preserved if Isaac enters one for the first time and then uses Glowing Hour Glass to leave, effectively allowing Isaac to reroll his Planetarium until a desired item is found.
• (Added in Repentance) The Boss Challenge Room re-rolls bosses on using the Glowing Hour Glass.

Synergies

• (Removed in Afterbirth †) (? Card) ? Card: Allows for infinite usage as the ? Card gets refunded upon usage.
• (Added in Repentance) 4.5 Volt: Allows for infinite usage in rooms where a lot of damage can be dealt, most notably boss rooms.
• (Removed in Repentance) 9 Volt: Clearing any room is enough to instantly recharge the hourglass, allowing infinite tries for best outcome.
  • (Added in Repentance) With (AAA Battery) AAA Battery the hourglass is instantly recharged.
• 48 Hour Energy pill: Allows for infinite usage as the pill gets refunded upon use.
• (Removed in Afterbirth †) The Battery: When the item is double charged and used it will also refund the used extra charge bar, making it possible to use it endlessly.
• (Added in Repentance) Book of Virtues: Any wisps lost in the previous room will be restored, and an additional Glowing Hour Glass wisp will be added on the middle ring. This wisp's tears have a 30% chance to petrify enemies.
• Bum Friend: Using the Glowing Hour Glass after the Bum Friend has picked up coins but before it has spawned pickups will restore the coins in the room but will still cause the Bum Friend to drop pickups. This can be used to repeatedly generate pickups from the same set of coins.
• Curse of the Tower: If used quickly after taking damage, Troll bombs will spawn in the previous room. If you have the (Safety Scissors) Safety Scissors, these can be harvested as normal.
• Dark Bum: Using the Glowing Hour Glass after the Dark Bum has picked up hearts but before it has spawned Soul Hearts will restore the hearts in the room but will still cause the Dark Bum to drop Soul Hearts. This can be used to repeatedly generate Soul Hearts from the same set of hearts.
• (Added in Repentance) Duality: Time can be reversed while inside one deal to go into another.
• (Added in Repentance) Eraser + (Added in Afterbirth †) Schoolbag: Using Glowing Hourglass to return to the previous stage will keep the charge Eraser received from entering the next stage.
• Habit: Allows rooms to be repeated infinitely as long as Isaac has enough health to take (Removed in Repentance) two ((Added in Repentance) three) hits, which are refunded on use.
• (Added in Afterbirth †)(Hairpin) Hairpin: If Hairpin is held while entering any Boss Room for the first time, Glowing Hourglass may be used indefinitely on said room to repeat the fight until you beat it.
  • Only applies after Booster Pack 5.
• More Options: If used after entering the Treasure Room for the first time, upon reentering the room, one item will have changed places and another will be new, effectively making More Options a choice of 3 items instead of 2. If used a second time, the items change back.
• (Added in Afterbirth †) Moving Box: Using the Glowing Hour Glass after retrieving it from Moving Box will not deplete its charge. Allows for infinite usage as long as Moving Box is fully charged.
• (Added in Repentance) Saturnus: Using the Glowing Hourglass will activate the effect of Saturnus again, essentially allowing for double the amount of orbiting tears, if the player returns to a room, where the tears created by Saturnus were not destroyed.
• Sharp Plug: Allows for infinite usage as long as you have more than 2 ((Added in Repentance) 1.5) full hearts as the hearts used to charge will be refunded upon use.
• (Added in Repentance)If Tainted Eden's active item re-rolls into Glowing Hourglass, it can be used immediately to return Tainted Eden to their previous state. This allows the player to have practically infinite attempts to keep their loadout of passive items.
• (Added in Repentance)If a use of Glowing Hour Glass by Tainted Lazarus involves changing to his other form - either due to room completion or by using (Added in Repentance) Flip beforehand, Glowing Hour Glass's charges will not be consumed. This essentially allows infinite retries of any room you enter as the form that does not hold the item.

Interactions

• (Added in Repentance) Bag of Crafting: The bag's contents will be reverted to its previous state.
• Car Battery: No effect.
• (Added in Afterbirth † / Removed in Repentance) Void: It is impossible to absorb a Glowing Hour Glass pedestal without using the item and preventing it from having been absorbed.
  • (Added in Repentance) The Glowing Hour Glass is absorbed like normal. Subsequent uses of Void send Isaac back to the previous room reverting most changes, nullifying many other effects that Void may have absorbed. Energy is still reset back to full upon each use, allowing for infinite re-tries of any room. This does, however, prevent you from consuming any further powers as you will instead reset the room.
    • Notably, the Broken Watch triggers the slow effect on every fourth room, based on the room counter which does not reset on use, allowing you to undo a fast room and get all slow rooms.
    • The Placenta re-rolls regeneration at the minute mark, allowing you to re-roll entering a new room shortly before the minute mark and almost guarantee a regeneration (mind the one-second animation tick on the clock).