A beast that was kept underground for 100 years thanks to a spell done by the four monster elders. While Chet and Mort were taking Chet's dad, Remulos, to see Monique for the first time in years, this abomination awoke due to the elders dying and it burst through the ground, hungry for SOULs. Before Chet, Mort, and Remulos ran into him, the beast had already obtained 9 SOULs + 1 monster SOUL (one of which was Monique as she was out shopping and the monster one was Cindy) and he only needed one more. The beast stabbed Remulos and took his SOUL and then engaged in a fight w/ Chet, who angrily ordered Mort to get out of there and go protect Patricia and Pudding. Mort tried to tell Chet that he didn't want to leave Chet alone, but this caused the Chets to both furiously snap at him which caused Mort to begrudgingly run away. The beast (?z?z?l) saw Mort's SOUL and tried to get it but Chet blocked it. ?z?z?l noticed Chet's SOUL and the two ran towards each other, both intent on winning.
Don't let ?z?z?l's appearance fool you. He's really fast, is made out of goo, and uses a big, serrated meat cleaver and karambit as SOUL weapons to attack people. He's also mostly blind as he can only see a person by their SOUL. He also wasn't always like this and his backstory is really tragic and f**ked up.
His goal: To get 10 human SOULs (getting monster ones as well does help a bit) and after that, destroy the universe.
Fight theme: Mother 3 unused Giygas theme and/or Giygas phase 2.
Megalovania: Horrorlovania
Also, the SOUL stealing thing was definitely inspired by Bete Noire from  camilaanims.