Octoling Assault: ~ Pump Track It Up ~ is the fifteenth stage in the Hero Mode of Splatoon 2. The mission can be found in the third sector, Beaker's Depot.
The map is a remake of Humpback Pump Track, with eight Mini Zapfish that need to be rescued, but are heavily guarded by Octolings loyal to DJ Octavio, all armed with Splat Bombs and Splat Rollers, making them much more difficult to defeat due to the range their Rollers can reach. There are also Toxic Mist generators located around the map that need to be destroyed before they can drain Agent 4 of their Ink and leave them vulnerable to being splatted by the Octolings. Most will Super Jump into an area, so they can use their Splat Rollers' range to their advantage to take out Agent 4's armor quickly.
There are three Special Weapons that can be found and used against the Octolings: Two Curling Bomb Launchers, and one Splashdown. The Splashdown is locked in a square box that requires a Key to open. Two can be found around the map, but one is needed to open the box the Sunken Scroll is contained in. There are also four Armor pickups around the map that can be collected to help protect Agent 4 against the Octolings and their arsenal.
The Sardinium is in a heavily-armored crate near the Octolings' Respawn Point, and the Sunken Scroll is nearby as well, requiring a Key to open like with the Splashdown.