Shin Megami Tensei: Digital Devil Saga

The first boss you encounter in the Karma Temple. Make sure you have a void/repel/drain ice spell handy, otherwise she'll use a skill called Hima Alaya, which does massive ice damage, and has a high chance of freezing you. If that happens, she will then attack the frozen character for critical damage, usually ending in death.

So long as you have an ice shield up, she will resort to using maziodyne, megidola and sonic wave. If you have null nerve, this will negate sonic wave, if you don't, just use panacea's on the affected members. Vasuki is weak against fire, so keep on pummeling her with the strongest agi- skill you have while keeping an ice shield up, and she'll soon fall.