Spinal Phase

Spinal Phase is the seventh stage in the Octo Expansion's finale.

Gameplay
Agent 8 must defeat a partially sanitized Agent 3 in a boss battle.

Agent 3 is armed with their, s, and has a large arsenal of special weapons at their disposal. They will always enter the arena by a Super Jump and activate a upon landing, with the exception of the  phase. Additionally, Agent 3 can dodge roll at any time as if they were landing with. Agent 3 will use the Hero Shot and Splat Bombs in all phases of the fight but uses a single type of special exclusively in each phase. It should also be noted that, like the player, Agent 3 is able to heal themselves over time, accelerated if they swim through their own ink.

If the player gets repeatedly splatted, they have the option to skip this phase, with each splat contributing to 20% Skip Charge, where the following dialogue will be displayed:

"After a fiercely fought yet bittersweet battle with the renowned Agent 3, Agent 8 emerged victorious..."

Phase 1
Agent 3 will land into the stage with a. After that, Agent 3 will fight normally. Agent 3 does have access to during this phase whenever their special is charged.

Phase 2
After taking sufficient damage, Agent 3 will Super Jump back to the spawn point on the UFO flying over the arena. Agent 3 will Super Jump into the stage and immediately activate the, trying to corner the player before setting it off. The Baller can be destroyed with sustained fire, however, both layers of the Baller have much higher health than usual. The rest of the battle continues normally, though Agent 3 can activate another once their special is once again charged.

Phase 3
Super Jumping back onto the UFO, Agent 3 will remain on top of it, firing off the in between volleys of Hero Shot fire and Splat Bombs. The UFO is difficult to reach with the 's fire, though it can be reached while standing on one of the platforms and it is low enough to throw a Splat Bomb on top of it.

Phase 4
Agent 3 in the final phase will start by using the Splashdown three times in a row. There is a period of rest between each Splashdown where Agent 3 is vulnerable, if enough damage is dealt to Agent 3, they will dodge roll out and continue into their next Splashdown. Agent 3 can perform their successive Splashdowns again once their special is charged.

Quotes
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S2 Icon Cap'n Cuttlefish.png Cap'n Cuttlefishgreen
"GYAAAH! Agent 8? Help meeee!"

"Agent 3's mind was hijacked by that crazy phone!"

"Agent 8! Get 'em before they get you!"

"Take down Agent 3, and get rid of that weird glowing goo on their head!"

"Agent 8! Don't mind me - just take out Agent 3!"

"It's not over yet!"

"Well done, Agent 8!"

"Untie me at once!"

}}

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S2 Icon Marina 2.png Marinagreen
"That's the central elevator. The battery is in there!"

"Cap'n Cuttlefish's and Agent 3's signals are close!"

"I sure hope the captain and Agent 3 are OK..."

"The heli? You think we need it?!"

"Good point."

"Huh? The elevator..."

"That's Agent 3! But..."

"It looks like Agent 3 removed the limiter..."

"The goo is gone, so it's probably fine..."

}}

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S2 Icon Pearl 2.png Pearlgreen
"You can make it to the surface with this!"

"Maybe they already made it to the surface?"

"Eight! We'll come get you in the chopper, so just wait up there with Cap, OK?"

"There are only so many chances to use it. We can't let it go to waste!"

"Thanks!"

"It stopped!"

"Who's up there?"

"Inkoming!"

"Are you serious? This is way too many specials!"

"Did we do it?!"

"It looks like Agent 3 is out cold... again. Will they attack you if they wake up?"

}}

Trivia

 * The icons for splatting a player used in multiplayer matches are displayed when Agent 3 is defeated.