New Game :
Complete the game and load your cleared saved game file to start with all levels, items, and stats from your previous playthrough. You will also get the Triple Rune, and the game wil become more difficult.
Play as Bosses in Free mode:
To unlock a Boss for play in Free mode, defeat that Boss in Single-Player mode.
To play the “Evil Storyline”, choose to keep your Wand when asked by the Diva Of Twilight after defeating the White Bishop.
To play the “Good” storyline, choose to give up your Wand when asked by the Diva Of Twilight after defeating the White Bishop.
After defeating Leonard and returning to Diva Of The Twilight’s Castle and Isaac becomes evil, you must defeat the other five sages with half of your original power.
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.