Mysterious Berserker (Patreon)

Starting in the next update, a mysterious humanoid will be stalking the halls of the dungeon's first floor, attacking unsuspecting students. She attacks without warning, yet is quick to flee when hurt. 

Some students believe her to be a vampire, due to her pale skin and red eyes, but the faculty refuse to believe any monster could be on the first floor at all. Who, or what might this woman be?