Once you defeat Leonard and get to the scene where the Diva of the Twilight threatens to kill the Wind Sage, keep the wand. You will become evil Isaac under Diva's control and can roam around to collect the lost spells for evil and let Diva win. However, if you give up the wand, she goes away leaving your friends alive, letting you continue. If you follow the pointers, you will find another wand. No matter what, Diva of the Twilight will still make her new castle.