It was really easy to locate Caster and "see" where she was. He moved towards the place, keeping as little noise as possible and using his magic to add the noise in her mind so she wouldn't hear.

Then she user her magic to cause him pain and he bit hard on his lower lip to keep himself from making any noise and giving away his position.

Once he was close enough he send a wave of water at her, hoping it would come as a full surprise.