Splatoon 2: Octo Expansion – How To Fight A Bonus Final Boss | Secrets Guide

The Octo Expansion for Splatoon 2 is surprisingly difficult. Even I, a master Squid Kid, struggled with more than a few of the challenge-based stages. There really are 80 stages total, which is somehow longer than the main game, even if the stages themselves are usually a lot shorter than the ones found in the standard campaign. Basically — there’s a whole heck of a lot to do in Splatoon 2, and it’s worth finishing everything.

Why? Because there’s still one final challenge to complete. I’m not going to just spoil it here — check below for lots more spoilers — but there is a totally unique encounter at the end of the yellow brick road. If you can complete every single challenge and get all those Mem Cakes, there’s a secret in the main arena to unlock. Not only will you get all the costume pieces for Octolings, you’ll also get a fight.

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How To Fight A Bonus Final Boss | Secrets Guide


To find a bonus final boss in Splatoon 2: Octo Expansion, you’ll have to do everything in the underground train network. Essentially, that means completing all 80 challenge levels. If you’ve picked up the thangs and fought the last boss, you’ll already know who (or what) it is — the fight is against a mind-controlled Agent 3, before leading into a final challenge level.

The battle against Agent 3 is surprisingly tough. You’ll have to beat all three rounds to defeat them, all without taking a fatal hit. Thanks to their bonus abilities, it gets tricky fast. The bonus final boss is way, way harder. Here’s what you need to do.

  1. Complete all 80 challenge levels and get all the Mem Cakes. (Skipped levels must be completed.)
  2. After finishing all 80 levels, a message will appear.
  3. Travel to the Central Station Hub using the level select menu.
  4. At the Central Station platform, go to the lockers and inspect them.
  5. After inspecting the lockers, you’ll be able to encounter an optional, super-hard version of the Octo Expansion final boss.

The bonus boss battle is a remixed, harder version of the Agent 3 fight. You’ll fight Agent 3 all over again, and it’s much, much tougher. If you’ve actually finished all 80 challenges, then you’re probably pretty good at Splatoon 2, but this is still a tough fight.