"Impending doom? That's ridiculous! What would that even sound li-" - Frost Queen
The Frost Queen is a monster in the dungeon that is also the monster's leader.
Her main interest is in enslaving female students and creating monster girls in order to take over the town.
If Julia has 1200 or more Support proficiency and lost 2 battles against normal monsters and 2 against monster girls, the Frost Queen will kidnap the Protagonist and Julia in the dungeon, realizing they're lacking in damage output.
If Ashley defeats her, the Protagonist can enslave her by casting a Chakram on her before Ashley breaks her neck.
If she wins, she'll enslave the Protagonist, Ashley and Julia but if Julia has her bracelet, she'll kill the Frost Queen.
If she wins and Julia lacks her bracelet, it leads to a bad ending.
If the Protagonist decides to enslave her, it's implied that the Protagonist, Julia and Ashley will punish her in some way later.
Trivia
- Her appearance seems to be based of a Yuki-Onna (Snow Lady) in Japanese mythology.