Wallbreaker Wave generator in Zegnautus Keep.
I've given much thought to the idea of suppressing the Lucians' magic, and while it will be some time until we have a working prototype, I believe we should have a fully functioning jamming device added to our magitek arsenal before long. Further combat data would certainly help speed along the development process—especially data related to the divine.
Chief Besithia's Journal: M.E. 720-XII-9th
Wallbreaker Wave is an imperial discovery in Final Fantasy XV that neutralizes the Lucian royalty's magic and even enfeebles Astrals. Seeking to invade Insomnia protected by the magical Wall upheld by King Regis, Niflheim Empire had begun developing technology to overcome it. The "wave" they had discovered produced exceptional results in real-world conditions, inhibiting the Kingsglaive's warping and spell-casting abilities—powers that operate on the same principle as the Wall. Niflheim discovered that the wave can neutralize not only the Wall, but all magical phenomena exhibited by Lucian royalty. Based on the data acquired from the encounter with Shiva, Niflheim also expected an enfeebling effect on the Astrals.
Story[]
Verstael Besithia put forth the idea of developing a jamming device that would neutralize the magic used by the Lucian royals and wrote about plans for building one as early as M.E. 720.
It is unknown if Niflheim used the wave during their encounters with Titan and Leviathan, but when Loqi Tummelt and his magitek infantry invade Lestallum during the Assassin's Festival, they deploy the Wallbreaker Wave to cut Prince Noctis from the power of kings, believing this renders him harmless. He can still warp, and Noctis prevails even without his magic. Cindy Aurum disables the generator that projects the Wave, granting Noctis back his powers.
Ardyn's device.
When Prompto Argentum finds himself in the First Magitek Production Facility, he is unable to conjure his weapons, forcing him to use a handgun provided him by Ardyn Izunia and other firearms found throughout the facility. This seems to indicate the Wallbreaker Wave is in effect within the snowfield wherein the facility is located. When Ardyn confronts Noctis at the train at Ghorovas Rift to tell him Prompto is being held in Gralea, he has a small device on his hand that he activates just as he leaves. What the device is for is never further elaborated upon, but as Noctis infiltrates the imperial capital, he finds his powers fading, unable to summon his weapons or use magic without the Ring of the Lucii. Thus, the device Ardyn had could be a trigger for the Wallbreaker Wave.
The console for operating the Wallbreaker Wave.
When he makes his way to Zegnautus Keep, Noctis discovers a large red generator near the throne room, and gets an ominous feeling from it. He turns off the device with a control panel in the throne room and regains his ability to use magic.
Though the wave is said to disable the royalty's magic, it doesn't disable the powers of the Ring of the Lucii. When Noctis finds the Sword of the Father from the Keep he is able to use it and store it as his usual arms even before turning off the apparatus that seals his powers. It appears that the Wave only affects specified targets; Ardyn appears unaffected, and specifically enables Gladiolus and Ignis to summon their weapons.
Behind the scenes[]
Noctis's weapon disintegrates from his grasp.
In the Omen short film, Noctis loses his ability to use magic, similar to what happens when his powers are sealed in Final Fantasy XV. This part of the film was patched into the main game as a dream Noctis has when he stays in Lestallum.
When the Wallbreaker Wave is in effect during Assassin's Festival, the air ripples in blue static effect 
.