Game:Riku

First battle
Here, you will be reunited with Donald and Goofy (after playing with only one party member, the Beast, for quite a while). The Beast will not join you in this party, so make sure your Strength and Defense are up.

His moveset is about the same as the battle in Destiny Islands, but now that he has the Soul Eater with him, they can be very damaging. He moves very fast too, so you may either Guard or Dodge Roll out of harm's way. Melee attacks are recommended for this battle - and like all other boss battles, heal when necessary. Good evasion, good timing, lots of physical attacks - these are sure to get Riku down rather quickly. If your stats are rather low, however, this can be a tiresome fight.

You may consider summoning Tinker Bell to restore your HP periodically.

Second battle
Here, you'll be fighting a possessed Riku. Before approaching him, re-stock Sora's items and make sure that he is in top notch condition. You are alone in this boss battle. It is strongly recommended that you equip Guard, Dodge Roll, and Glide. Riku's HP is made up of several bars. In his first HP bar, he'll attempt to toy with you, passing around you and executing his standard two-hit combo; just simply dodge and attack him. Whatever combo that you use, try to refrain from executing the combo finisher, like all incarnations, Riku has fast recovery and devastating counter attacks. If you have equipped Ars Arcanum, save it for later. Also beware: magic does little, if not nothing, to this boss.

When you drain his first life bar away, Riku will start using a new attack, he'll spin around while swinging his Keyblade, similar to Sora's vortex. He uses this attack very often, mostly to break your combos. During this time, try keeping yourself from a safe distance, by not too far, or Riku will make a high leap and attempt stab you with his Keyblade, creating shockwaves. Now it will be a good time to use Ars Arcanum, just use a few time, and try saving your MP, you'll be needing it later.

Eventually Riku will conjure a ritual-like move, where purplish auras surround him. During this period, his speed and agility increases, and he gains two new attacks, one involves throwing his Keyblade on you similar to Strike Raid, and his infamous Dark Aura. Fortunately, his thrown Keyblade can be deflected either by guarding with perfect timing or just strike it (again, perfect timing), for each successful deflects, Riku will receive damage and be left stunned for a moment. Seize this opportunity and bash him with all you've got.

When Riku's health bar drops to his final one, he'll become more and more aggressive, he no longer taunts you and uses Dark Aura very often (watch out for the phrases "Behold the power of darkness!" and "Open your heart to darkness!"). Riku's Dark Aura is a predictable move, but it can be difficult to dodge. When you see him floating and charging, keep you distance from him and start to High Jump. Immediately execute Glide and glide in circular fashion. Eventually you'll land again, repeat the phrase and start Gliding, Riku's finisher covers about 60% of the arena, so it'll be pretty hard to evade it. Alternatively, when he charges to one particular end of the arena (he usually starts with the top left corner), jump and stay there: Riku will not charge into the same area twice. Stay there until the finisher is executed (because he will not hit that area).

Attacking and counterattacking are good tactics while Riku is in this form, just pay attention to what he says and heal occasionally and you should be fine.

Note also that aside from the first hit, he cannot Dark Aura you when you stand RIGHT next to the computer/desk/worktop. However, he will Strike Raid and combo you IMMEDIATELY afterwards.

When Riku's health hits critical, be sure to finish him as fast as you can, he'll pull Dark Aura very often, thus prolonging the fight. Aside from that, he'll start to keep his distance from you, so track him down and continue hacking him and you'll eventually win. Suggested Keyblades to use other are the Ultima Weapon and Olympia - but ultimately, no matter what Keyblade you use, fight Riku tactically and you will take him down..

Quotes

 * "Come."
 * "Ha ha ha!"
 * "Well? What now?"
 * "Here it comes!"
 * "Is that it?"
 * "Feel this!"
 * "Welcome to Oblivion!"
 * "Useless!"
 * "Behold the power of Darkness!"
 * "Surrender!"
 * "Show me your power!"
 * "Open your heart to Darkness!"
 * "You're nothing!"
 * "Now, here's my true power!"
 * "It's over!"
 * "I've failed you...Failed you."

Video
Riku, possessed by Ansem Ek2huPFz2qA