When Riku returns to Castle Oblivion from Halloween Town, he's immediately challenged to a fight by Lexaeus. Riku accepts (with no other choice) and the two battle. Lexaeus won't take it easy on Riku, and can be a pretty tough fight. Dodge and card break his attacks while trying to get as many attacks in on him as you can. If you can, this would be the perfect time to get into Dark Mode. Dark Aura and Dark Firaga can prove to be a big help in this battle. Lexaeus' attacks include:
- Lexaeus throws up his weapon and it lands with Riku as a target.
- Lexaeus slashes his weapon around in an attempt to get Riku caught in the combo.
- Lexaeus brings a rock up from the ground and punches it. Its remains spread out and are aimed at Riku.
After Riku defeats Lexaeus, he says he's impressed but quickly escapes after telling him that the darkness will take him eventually. Riku is then taken to a new area - an area full of darkness. Ansem tells him that once Riku wakes up, his heart will be Ansem's. King Mickey, once again, comes to the rescue. He tells Riku to fight Ansem and not to give in to the darkness. Riku awakens again to find that his heart still belongs to him. Riku is then told that Marluxia has just been killed by Sora, and is given the Destiny Islands card. Move on to your new destination.
Riku never realized how much he missed his home until now. He sees Selphie, Wakka, and Tidus, only for them to disappear. From where you start, clear the room of Heartless and use the north door. In Room 2, use the left door. In Room 3, use the left door. In Room 4, use the north door. In Room 5, use the left door and you'll face the boss battle of Destiny Islands after a lengthy cutscene.
Darkside is an easy boss battle frustrating only because of its large amount of health. Its health reaches a fourth bar, making it a rather time-consuming battle. Use Sleights and combos to finish this boss off. Card break if you want to, but it's really not necessary as long as you have the right Item Cards. Darkside's attacks include:
- When Darkside brings his fist down and slams it onto the ground, that's his way to summon Shadows. Get rid of these quickly so they don't get in the way. Although they're small, they can easily get annoying.
- Again, Darkside slams his hand down onto the ground. This time, however, instead of summoning more Heartless, a shock wave is made by the impact. An attack that is relatively easy to avoid.
- A large sphere is emitted by Darkside. Another attack that is easily dodged.
- Darkside emits a large sphere once again, except this time, it doesn't aim for Riku. It aims upward for the sky, and splits into many smaller spheres. They rain down on Riku, making this a little hard to dodge. This is the attack of the battle to avoid.