The Toilet of Doom is Hat Kid's stray soul possessing a toilet and a boss in the Subcon Forest. It acts very hostile, and tries to attack when Hat Kid walks near it. It serves as the titular main antagonist of the eponymous Toilet of Doom act.
In the first phase, the Toilet will teleport around the arena, eventually stopping to release several toxic bouncing bubbles. One of which will contain a fruit bomb which must be picked up and thrown to deal damage. After being hit, it will jump in the air and create 2-3 shockwaves on the ground before jumping to the center and causing several of the surrounding cages to sweep across the arena randomly. During this phase, the Toilet will glow blue and can be hit by swinging into it using the grapple point above it.
After being hit 4 times, the Toilet will then jump to the center and release several bubbles that surround and float around the pool, one of which contains a fruit bomb. Hat Kid must use the grapple point to swing and grab the Fruit bomb while avoiding any toxic bubbles among the others. While this is happening, the Toilet will create singular shockwaves every few seconds, leaving it open to attack.
After being hit 2 times, the final phase begins, in which the Toilet will jump to the center and summon 3 cages containing spirits, which it will use to supercharge a fruit bomb to a massive size. If it is allowed to detonate, Hat kid will be defeated instantly and will have to restart the battle. To damage it, Hat kid will need to jump across the 3 cages to reach the top of the bomb where the Toilet resides, hitting it will immediately stop the bomb. It’s will then jump in the air towards Hat Kid and create 3-4 shockwaves until it is stunned, allowing Hat kid to attack it. It’s last attack is to teleport away from Hat kid and cause more cages to sweep across the arena while turning blue, leaving it vulnerable to damage. The Toilet will repeat these attacks until it is hit 5 times, after which it will explode and be defeated.
The Toilet of doom went through two main builds before it's final version, which are described below.
Prototype/Alpha- Jumps towards Hat Kid, leaving a Brown substance on the floor that stuck there, most likely hurting Hat Kid if she stepped on it. It could also spin around, spitting the brown substance in all directions around it. It would also do a belly flop attack, in which it jumped high in the sky then attempted to belly flop on Hat Kid, which would allow Hat Kid to hit it after it comes down. It would have taken 25 umbrella hits to kill, and would have exploded into many pons after death.
Late Alpha/Beta- The ground itself was made out of a dangerous green substance that looks similar to the stuff in the center of the final Toilet of doom arena. The arena had 8 platforms around the dangerous center of the arena, in which the toilet would be. It could send out a shockwave (Similar to the final one, but taller and slower, and would have gotten smaller and smaller the further it moves from it's original position.). It could spin around, spitting a dangerous brown substance over the ground of the arena when doing so. This substance would, shortly after landing on the ground, turn into a bouncing brown bubble that could hurt Hat Kid. The toilet would also periodically jump and land on one of the 8 platforms, making it sink into the dangerous substance below. These platforms would then later reemerge from the ground, sometimes as dweller platforms. When standing on these platforms while holding one of the purple fruits found near the center of the arena, the fruit would turn red and start an explosion timer (Similar to when the player has one near an actual dweller in the final game). This fruit could then be thrown at the Toilet to stun it for a short time, letting Hat Kid get a few umbrella swings at it before it gets unstunned. Later in the fight, the Toilet also would have started to rain large amount of the brown substance from the ground at once over 4 platforms. These platforms would then sink into the green substance below just like the Toilet had jumped on them. It would have taken three rounds oh hitting the boss like this to defeat it. This version was most likely removed due to it's ridiculous length.
Most of this information was gathered based on the video at https://youtu.be/PLebj2Tp7kY. Additionally, three cut songs Toilet of Doom songs from the "OST in Time" (Early ost made by Eric Gleiser) have been found, those being:
Toilet of Doom (Prototype) - https://youtu.be/cYk5HK_1nQg
Toilet Boss Hero Loop (Beta) - https://youtu.be/YoWjz4c5xGQ
Toilet of Doom Intro (Prototype) - https://youtu.be/PS6fTSsG2o4 (This version was incomplete. It is unknown if this version of the intro theme had ever been completed and we haven't found it yet, or if this was all that had been made)