In season three , Nyssa is against Oliver when someone ( later revealed to be Thea after being drugged by Malcolm ) is responsible for Sara 's murder .
In season three , Nyssa trains Laurel Lance ( Sara 's sister ) to follow in Sara 's footsteps .
In season three , Nyssa is against Oliver when someone ( later revealed to be Thea after being drugged by Malcolm ) is responsible for Sara 's murder and trains Laurel Lance ( Sara 's sister ) to follow in Sara 's footsteps .