Chaos vs. Order

Chaos vs. Order, also known as Final Fest or Splatocalypse, is an upcoming Splatfest event in Splatoon 2. It will be held in all regions for 72 hours from 2019-07-18 to 2019-07-21. It was announced at the Splatoon 2 World Championship 2019 and on social media on 2019-06-08.

Details
This Splatfest will be the final Splatfest held in Splatoon 2. In this Splatfest, a new Shifty Station layout will be introduced, alongside the return of every Shifty Station layout introduced prior. For the first 48 hours, all previous layouts will be part of the Splatfest Battle rotation. For the last 24 hours, the new layout will be playable.

Four pieces of headgear (two for each team) will be available in a Squid Research Lab Report article on the Nintendo Switch News applet in late June.

A trailer revealed the alignment of characters and weapons, detailed in the table below.

Shifty Station's outcome
Although this is the final Splatfest, Nintendo announced that the Version update for Splatoon 2, which will go live after this Splatfest ends, will introduce Splatfest Battles on Private Battle mode. Every Shifty Station layout, including the unknown Final Fest layout, will be available in this mode and the host will be able to choose the team ink colors from a list of all 51 Splatfest color schemes from every region. Every stage, including the regular stages available in the base game, will have a day and night mode.

Trivia

 * In the promotional art, Callie is shown wearing Pearl's crown from the Octo Expansion while Marie wears Marina's headphones.
 * It is widely suspected that the outcome of Chaos vs. Order will affect the plot of a sequel game, in a similar fashion to Callie vs. Marie.