Like all rollers, the Dynamo Roller can cover the ground and can fling a larger amount of ink at medium range. Compared to the Splat Roller, this roller is slower, but covers a larger area while rolling and throwing Ink. You need to find the sunken scroll in the Octobot King boss fight to obtain this weapon. It appears out to outclass the other main weapons.
"Using the blueprints as a starting point, Sheldon rigged up a motor to the roller base. Cumbersome to use, but delivers a powerful burst of ink when swung."