Inkling pulls out a large megaphone-like machine and places it on the ground. The machine then emits large damaging sound waves which can be angled. Then, Killer Wail replaces the sound waves with a blast of ink, covering other fighters in it. While somewhat similar to Zero Laser in function, it differs in allowing Inkling to act normally while the Killer Wail is active.
The Killer Wail appears as a special weapon in the original Splatoon. Like all special weapons, it is charged by inking enough ground. When used, it lets out damaging sound waves which damages opponents and passes through walls. Like its appearance in Ultimate, Killer Wail does not cover surfaces in ink, but opponents it does not immediately splat will be covered in ink. In contrast, it cannot be moved at all once deployed.
Although it is no longer a playable weapon in Splatoon 2, a customized Killer Wail called the Princess Cannon appears at the end of the final boss battle of the game's Octo Expansion and on the Splatfest-exclusive stage MC.Princess Diaries, used by Pearl to destroy the final boss or unleash an extremely large and powerful Wail on the opposing team, depending on which makes it to her first.