Nocturnal is usable, but has flaws in its design.

Diurnal is more mp efficient, it has Shields that can handle anything baring 3 fights at end game (2 savage and ultimate) despite being toed to an ogcd every 30s and a cd every 2 mins, and Neutral Sect the lv 80 ability synergies better with Diurnal ( Hello asinine 400mp cost extra for nocturnal AB with the same exact effect and potency as diurnal AB).