The Other Side of the Heart
After the opening scene you receive the Key of Beginnings . Twilight Town is pretty small but it's a great place to level up. You'll want to take full advantage of this because your first destination will be your last one in this world. When you are done leveling up, head to the Room of Beginnings to find Vexen still pursuing you.
BOSS - Vexen
Vexen fights exactly like your previous fight with him but he uses a new sleight called Slide Break. Vexen summons an ice sword and dashes towards you to start a three-hit combo. This attack can kill you. You'll definitely want to watch for it and card break it. He doesn't always use this attack, only when he has low health, but it's something to watch out for before you get too excited for a victory.
Remember to keep your Potions/Hi-Potions for when you have a high reload counter. Jafar is great for finishing out the battle, but Sonic Blade is also great because it does so much damage.
As you head to the 11F Exit Hall you'll meet Riku once more.
BOSS - Riku
Riku isn't much tougher this go around then the previous time. He still has the Helm Split sleight and adds Dark Firaga to his arsenal. He's still hard but with your increased levels and new cards he should be easier than your previous fights. Use Jafar and Cures, Mega-Ether, and Oogie Boogie if you need. Focus on breaking Riku's cards and you'll have a much simpler fight, as you can negate all the annoying attacks he has. Like all fights, you can simply use a Sonic Blade deck to melt through Riku and win easily.
After the battle you'll receive the Destiny Islands World Card. Donald and Goofy will leave as Friends, so you'll be going alone through the next world.