Vanitas Remnant

Vanitas's Sentiment appears as the secret boss found in the Keyblade Graveyard in Kingdom Hearts Birth by Sleep. Before attacking Terra, Ventus, or Aqua, its battle must first be accessed by entering a dark portal with a picture of the charm found on the end of the Keychain found on Vanitas's Keyblade, similar to encountering an Absent Silhouette. After entering the portal, Vanitas's Sentiment forms from a sphere of dark energy, similarly to Vanitas's creation. Vanitas's Sentiment drops a Hidden Ore when defeated, then disappears in the same way he appeared.

Strategy
Vanitas's Sentiment uses a skill set similar to the true Vanitas, but with more powerful versions of Vanitas's attacks and the ability to heal itself whenever the player tries to do the same, excluding healing by Potions. Each of these tactics has the potential to instantly drop the player's HP into the "Alarm Zone", thus the boss should be approached with caution. It also has some attacks that Vanitas could only do with the X-Blade, both complete and incomplete.

Some differences in Vanitas's Sentiment's moveset include the fact that its standard behind-aerial attack can hit multiple times, time before the attack when the boss freezes in place significantly shorter. The fireballs it shoots fire at a much faster pace.

Vanitas's Sentiment also has a fair share of new tactics in its arsenal, however, able to dash around in the shadows before several dark, crystalline and floating blades attack the player from both sides. When the boss holds its blade above its head, the Keyblade it holds powers up, leading to several powerful slashes, the combo finishing with a long-range slash in the shape of an "X" that will home in on the player unless it comes in contact with an obstacle beforehand. It may also surround itself in darkness, which then summons "shadow" versions of itself that perform aerial combos. It may be hard to dodge, but it is possible. All you have to is to spam your dodge roll while running around it (at least when you're playing as Ventus or Aqua). If you are playing as Terra, your best chance of avoiding this is getting as far away from Vanitas's Sentiment as possible so that the shadows will take longer to get to you, but you must still be extremely careful, as Terra is slower, and if just one catches you, it is over, as you will most likely not have enough time to dodge the next shadow.

Not only this, but Vanitas's Sentiment will then proceed to power up, surging with energy, attacking its opponent from beneath. It should be noted that several of his attacks can cause the player's view to be obstructed by darkness for a certain amount of time, making it easy to be hit by any follow-up attacks he may use. Vanitas's Sentiment also has the ability to perform Vanitas's Shoot Lock, Dark Cannon, firing a massive dark energy beam with a relatively long range directly in front of it. The attack is easily avoidable, however, and it also leaves the boss open for attack.

It is best that the player keep a continuous hit-and-run pattern going during this battle. Victory is simply determined by the proper timing of guards and attacks, as well as the equipment of proper Deck Commands. It is also advised that the player not attempt to use their Shoot Lock, as it will leave them vulnerable to Vanitas's Sentiment's more powerful and fast-paced attacks. If one follows this tactic, the battle should not be overly long. It is, however, a very difficult fight, so patience is a must.

Video
Video:Kingdom Hearts: Birth by Sleep Vanitas's Sentiment Boss Video:Kingdom Hearts : Birth by Sleep - Vanitas Lingering Sentiment Defeated (Whole Fight with Aqua) Video:Kingdom Hearts Birth By Sleep - Terra vs Secret Boss (Lingering Sentiment Vanitas)

Trivia

 * Both Vanitas's Sentiment and the Lingering Sentiment, a similar boss in Kingdom Hearts II Final Mix, appear in the Keyblade Graveyard.