-When you meet up with Farah again after the brothel, there will be an intermission sequence where Mahasti will attack you. Climb up to the save fountain, then down to a platform where Mahasti will be waiting for you. Use whatever fighting tactics you prefer. If you get knocked off the platform, rewind time and evbade the attack. Eventuallyt you will transform into the Dark Prince, and Mahasti will run away. When chasing her, always run to the right, kill the enemy on the platform in between to fill a sand tank, and heal. After that, when you grab the ledge of the platform Mahasti is on, slow time and jump up. Slash at her until slow time ends and she jumps again. Repeat this until her health is depleted. You will enter a deadlock that you will have to win. If you lose, Mahasti will jump across the arena, and you will have to try again.
-Stay in the corner of the first platform you start on when you start battle with Mahasti. Then, constantly block her attacks and attack by using counterattacks. If you get kicked into the wall or off the ledge, rewind time. When you become the Dark Prince, attack Mahasti until she jumps back to the other platform. Get to her, but before you jump onto the platform slow down time and attack her as much as possible. Continue this until she is defeated.