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Ventricle Razor is an activated item added in Afterbirth.
- When used for the first time, Isaac creates a blue portal under where he is standing. The next time he uses the item, he creates an orange portal under his feet. Isaac can then walk over either of the portals to teleport instantly to the location of the other one.
- Activating the item more than twice will replace the older of the two portals.
- The portals can be placed in any room. However, if a portal leads to a room with a negative grid index (i.e. Devil Room, Angel Room, I AM ERROR room, Crawl Space, Boss Rush, Black Market, Mega Satan room, or Blue Womb portal room), Isaac will not be able to enter the portal.
- This item can be used to escape Challenge Rooms or the Boss Rush.
- The Amnesia pill does not remove placed portals.
- Upon teleportation, Isaac is granted with a short invulnerability period which can be abused to trigger Blood Donation Machines and Devil Beggars without losing health by placing a portal just next to it, teleporting, and touching the Donation Machine or Beggar in the same move. This trick is particularly useful for The Lost. The teleportation trick can also be used to escape Curse Rooms without taking damage.
- Portals will stay even if the item is dropped or changed.
- The item can prove useful in close quarters combat, allowing the player to attack one side, then dodge attacks and jump to the other side of the room to attack the enemies on that side.
- Upon entering a new floor, the previously placed portals will disappear, so the player doesn't crash the game by entering the previous floor.
- Car BatteryCauses Isaac's activated item to activate twice on each use.: No effect.
- A ventricle is a hollow part in an organ.
- The colors of the portals are a reference to the Portal Gun from the Portal series, whose portals share the same colors and functionality.