The image becomes warped (distended) as Luka uses Fallen Angel Dance
A secret skill to unify a holy wave and avoid attacks. It seems particularly effective against angels.
One of Luka’s skills, the Fallen Angel Dance is a skill which Luka activates under the influence of holy power while he is asleep. When attacked, Luka will evade it. The effect used is a shorter version of the "sleep waves" as Luka is falling asleep in the beginning of the game just before he speaks with Goddess Ilias.
In Chapter 3, Luka finally awakens his angelic powers against Archangel Ranael and can use Fallen Angel Dance. This particular move is extremely effective against angels, even moreso than Sylph and Undine combined.