The Legendary Knight Returns is the eighth mission of Devil May Cry.
Walkthrough (lower difficulties)
Dante starts out in an "interlude" phase: the mission does not technically start until Dante jumps across the gap ahead (this is a scripted long-jump) and enters the door. Prior to doing this, damage, Red Orbs collected, time and item use will not be counted towards the final mission result.
If following this guide, the first thing to do is to double back to the waterways and do Secret Mission 5: One Eyed Evil. Once this is done and the player has performed any farming for Red Orbs they may wish to in the other parts of the castle, proceed back to the bedroom and jump across.
This places Dante in a room with a Divinity Statue and an upper floor with some Red Orbs. Jump up and proceed through the door, then leap up to enter a circular arena to be ambushed by a familiar foe.
Boss: Phantom
Phantom, despite his boasting, is largely the same as when he was fought in Mission 03: Destroyer of Ardor. See the section there for a list of his attacks. He only has one new trick, his meteor attack: for this, he stops moving and fires an enormous fireball diagonally upwards from his abdomen, causing fireballs to rain down from the sky for a period afterwards. The attack can be cancelled if Phantom is made to flinch, even if he has already fired the fireball into the air: if he flinches, the meteors will never come down. After the attack Phantom's fires fade and he is briefly left incapable of action while he recovers.
As before, he is vulnerable to attacks on his abdomen and mouth, and particularly vulnerable to Air Raid and Helm Breakers delivered after using Air Hike if the player has it. In this battle there is also a special victory condition: if the player can get him to jump and land on the glass in the middle of the arena five times, the battle instantly ends no matter how much health Phantom has left.
After Phantom
Exit the arena through the gate that opened, and drop down to find a key item, the Trident. This is the required item for operating the castle's portcullis. In this area, Red Orb Caches are located on the head of the horse statue on the left and on top of the small pillar in the alcove to the right, while a Blue Orb Fragment is located on the high platform behind the horse statues: this can be reached with a wall jump or Air Hike, or with a Stinger long jump from the boss fight arena. If Dante accidentally falls into the hole between the horse statues, it is possible to get back up with a wall jump.
Dropping through the crack in the floor will place Dante in a room with the castle's drawbridge mechanism: slash at the lever with the white glow around it to open the drawbridge. The exit to this room is around the other side of the mechanism, but before opening the floor hatch, examine the nearby skeleton. This gives Dante a new weapon, the Grenadegun, a high-powered firearm that fires explosive projectiles with some splash damage, but has a recoil animation (though this can be skipped by rolling or jumping) and cannot be used in the air. After taking this, use the hatch.
This takes Dante down the ladder in the room where the fourth Blue Orb Fragment was back in Mission 01: Curse of the Bloody Puppets. Go between the chains and examine the device by the wall: this will raise the portcullis, but it will start lowering again immediately. The goal is to quickly jump over the raised portcullis, dashing out the door and down the stairs, exiting into the room where the third Blue Orb Fragment was in Mission 1 and getting through before the portcullis closes too far. Fighting the enemies along the way will not leave enough time for this, so it is a simple matter of running as quickly as possible: Devil Trigger helps with this. If it is too low to walk under, it may still be possible to get through with a roll by turning Dante side-on. If Dante fails to make it, he can go back up and raise the portcullis again to make another attempt.
Once Dante has made it through, do not exit immediately: there is another Blue Orb Fragment located in the water over the railing to the right. Then go through the door to finish the mission.
Higher difficulties
During the "interlude," Phantom is still present in the fountain courtyard, and can in fact be fought here an unlimited number of times by simply exiting and re-entering the room: this is a common tactic for farming Red Orbs. As before, Fetishes will be present along with the Marionettes on the path down to the exit after operating the portcullis.