Divyat was a being of cold rage, one that had what was rapidly growing to have absolute control over his qi and the ability to infuse it into his techniques. The midnight monsoon was a water attributed technique and while Divyat had the water attribute, it was a secondary attribute that came together with the wind attribute to make his ice attribute.
It didn't have as much power and effect when utilizing the technique as someone who was really born with the water qi spirit root. The only reason why so far it was so dangerous was because of how robust and effective his qi was. Hut right now, almost without paying full attention to it, Divyat had sunk in the concept of the frigid ice into the technique, changing it from a water technique to an ice technique.