I turned the game on for the Halloween tower and it turns out there was the moon in the back of the tower menu with the witch flying in front of it. There was tons and tons of bats flying around too. Maybe they just plan on using the assets for both the halloween week and The Pit or maybe the classic arena will be something else entirely.
Anyway, the Halloween tower was hilarious. It was just like the 4th of July tower, with the modifiers sporting brand new looks then a final match were they're all enabled.
You had to fight Revenant Kitana, Revenant Kung Lao, Revenant Sub-Zero, Revenant Jax, Pharaoh Ermac, Vampire Mileena and Kraken Reptile. Final match was against Jason.
Modifiers included slippery puddle of bloods, candy corn missiles, jack-o-lantern falling bombs, laughing skulls cyrax bombs, klose kombat (surrounded by a spider web complete with Krypt spider jumpscares DURING the match and vampiric health steal.
The final match against Jason was crazy.