The Killer Wail fires extremely large sound waves made of the player's ink color that are unobstructed by buildings and other obstacles. It does not spread any actual ink, but any opponents that are caught in the sound waves get splatted. It is also in Super Smash Bros Ultimate as Inkling's Final Smash.
Like all special weapons, the Killer Wail must be charged by splattering ink on the ground. Once charged, the player can click the right analog stick to utilize it and aim where they want it to fire. When launched, a message with the player's image and the special used (in this case the Killer Wail) will appear on the right side of the screen for teammates to see.
Fire it through walls where unsuspecting enemies can get a surprise splat.
Use it when enemies are hiding. It will give them a splatting surprise for hiding.
If the player is getting chased into a corner, they can use their Killer Wail on the chaser to escape being splatted.
Fire directly at the enemy spawn to delay the opponents or splat a careless enemy.
The Killer Wail is great for taking out enemy chargers. While it may not splat the charger, it may force the charger to get off his or her perch, making them vulnerable.
Be alert if any opponent has Killer Wail in their kits. Keep in mind that even walls do not obstruct the Wail.
When a Killer Wail user goes around a corner, they might start casting it to lure the player into a position where they can be splatted. Be extra careful around corners.
If the player is in a large and open area where the waves will be easy to avoid, follow the side of the wave, and splat whoever is using it.
Killer Wail leaves a 2 second delay and a mark to show where it will hit before firing. Use this time to escape.
Some Special Weapons such as the Kraken are invincible to the Wail. If the player is trapped and cannot dodge the Wail entirely, activating the Kraken will assure their escape.
Try fighting DJ Octavio and practice dodging Killer Wails as he uses it as one of his weapons.
There is a delay of about 2 seconds at minimum for aiming, firing and the recovery time, without Special Duration Up. Use this window of time to splat the inkling with the Killer Wail.