Spreader Splatfest
From Inkipedia, the Splatoon wiki
Walkthrough
This article hasn't been written yet but will be soon!
Sunken Scroll
If you need help finding the Sunken Scroll, go to this video [1] and skip to 3:17. Neither the writer nor this site owns this video. Video is property of Jirard "Dragonrider" Khalil AKA The Completionist and That One Video Gamer. Subscribe to their YouTube channel if you haven't!
Amiibo
There are 3 other versions of this level that can only be played through their respective Amiibo.