Kenkyu

Frigore Lusorem is the power to cool one's legs to a temperature so low that they glow bright blue. The style literally meaning "Freezing Kick". Horus uses Haki to contracts his muscles to such an extreme degree that the body grows colder. Since the temperature of the item is determined by how energetic its constituent particles is, compressing a solid makes his legs colder since the movement of the particles will be limited by their increased proximity.

Horus takes advantage of this by compressing his muscles with Haki to such an extreme extent that he lowers his body temperature. He then uses his lower temperature to freeze his targets with his strikes, and even freeze water vapor in order to generate ice from thin air. This allows him to take down stronger defenses, by freezing them, then shattering them. Though this does not always work.