Instructions
Getting to Xigbar
Return to Twilight Town after defeating the MCP (Master Control Program) in the "Space Paranoids" level.
Go to the Underground Concourse area in Twilight Town. This area has been blocked off until this point in the game. Feel free to explore the different exits, but you'll ultimately have to go through Exit 4, Tram Common.
Go to The Woods and make your way to The Mansion. Again, feel free to explore The Mansion; when you're done, proceed to the Library and into the Computer Room.
Speak with Pence and respond with "Sea Salt Ice Cream" when prompted. This will cause a ray of light to appear. Do any last minute exploration, save your game and touch the ray of light when you're ready. You will then be in an alternate Twilight Town.
Proceed to the Basement Hall and enter the Dark Portal to reach Betwixt and Between. You'll get ambushed by Nobodies but someone will appear to help you. After the battle and subsequent cut scene, continue to The World That Never Was.
Fight your way through this world, following the linear path from the Alley to Between area, where you begin, to the Hall of Empty Melodies, where you find Xigbar.
Defeating Xigbar
Dodge Xigbar's attacks. His fighting style is similar to that of a Sniper Nobody and he begins by jumping onto a balcony and shooting at you.
Run around the arena until you get the "Break" command request. Execute a Break and use Warp Snipe to make him fall to the ground.
Be aggressive. Xigbar will take breaks to "Reload." When he does this, attack him until he warps away.
Listen to Xigbar's attack cues. Halfway through the battle, he'll start using a large laser attack. When he does this, use Warp Snipe to attack for high damage.
Take opportunities to heal. When Xigbar is at about one-third health, he will start using a massive attack, preceded by him shouting, "You're gonna pay." Heal when he says this and then run in a circle as fast as you can to avoid his attacks.
Repeat the pattern. As Xigbar gets weaker, his battle pattern gets faster, so take every opportunity to attack and victory will be yours.
Save your game and proceed to the next area after defeating Xigbar. After the cut scene, you will receive the Oblivion Keyblade.