The priestesses sang to preserve the dragon's deep slumber, but one wonders if a single phrase of their song ever reached the dragon's ears. They're Hexers with the appearance of plants, tends to use hexes which are usable by the players, and they lacked melee attacks. Once defeated, they'll have a chance to emit poisonous fog.
Contrary to common belief, while the Sanctum Priestess Tiara they wear is supposed to be resistant to Profound Still if worn by players, here, they still can be silenced by the spell, once silenced, they're no more than fragile flowers. Besides, they can be allured by Yearn sorcery and Alluring Skull.