Null

Null is a secret World that is accessed by using the Wrath sin item on the boss in the final room of Droids HQ. Using that item or spawning the boss under the effect will instantly kill the boss and transition to this world, without spawning the button that wins the run in the boss room.

Null can not be accessed at Ascension 15, presumably to prevent skipping the boss fight entirely. Activating Wrath will instead incur its effects normally, while the boss is immune to its effects.

Environment
Null has a blackish purple color scheme, with granite walls and floor. This world will always take place at night.

Upon entering Null, all of your items are removed, your abilities are disabled, and you are given a Singularity Sword. The first room is simply a spinning rune of the floor with a button on the center. The second room contains a single Friendly Droid that you are forced to kill to proceed. All proceeding rooms will be empty except the last room, where there is a spinning Rune with a Wrath Sword on the center. Picking up this sword will end your run and give you a win and rewards.

Trivia

 * Null is one of the four secret worlds in the game, the other worlds being The Darkness, Astray, and Respite.
 * Previously before update 1.5, Null was always accessed after Atomic Factory and comprised of a single spinning Rune with an elevated button that ends your run with a win when pressed.
 * It was possible to set the time to Day using a Lantern or Illumina as it did not clear your items at the time.
 * Null's position as a world is still argued over.