A secret fallen angel skill to cut through space and time. It has very high damage for low SP use. It seems to be compatible with the power of wind...
Flash Kill is another skill Luka uses when under the influence of holy power. It is a single slash that apparently has the power to distort space and time, as Luka was able to cut and destroy Kraken's Aqua Pentagram, an ultimate defense ability that utilizes the power of space and time.
After Luka finally awakes it in Chapter 3, it replaces Lightning Sword Flash, has a 2 SP cost, and is compatible with Sylph.