Hollow Knight

Behaviour
The Hollow Knight is the Vessel that sealed away the Infection. It is one of two final bosses of the game.

Upon breaking the seals on the temple by destroying the three Dreamers, the player is allowed entrance in order to fight this boss. To begin the fight, the player must break the four chains holding the Hollow Knight.



Phase 1
The Hollow Knight has multiple moves:
 * Nail Combo: Slashes their nail at the player multiple times.
 * Infection Pillars: Jumps and tries to strike the player from above, impaling the ground when they land, causing fire-like pillars of Infection to briefly charge up and then erupt from the ground.
 * Nail Lunge: Dashes at the player with their nail pointed forward.
 * Teleport: Warps from one part of the stage to another.
 * Parry: Raises their nail in a defensive stance. If the player strikes twice with their own nail, the Hollow Knight quickly counters with a slash.
 * Infection Shot: Launches orange balls of Infection from their chest in a sweeping arc at the player's general direction.

Phase 2
Phase 2 is announced by the Hollow Knight screeching loudly, stunning the player. During the second phase of the battle, the Hollow Knight gains some new attacks on top of the old ones:
 * Self-Mutilate: Stabs themselves repeatedly with their nail. While not a direct attack, standing in range of the nail as it comes through the back of the Hollow Knight's body will deal damage. In addition, they take almost no damage from the player while in this state.
 * Engorged Slam: Floats in the air, homing in on the player before slamming down to the ground. This repeats multiple times. After this attack, the Hollow Knight is left vulnerable for a few moments.
 * Infection Barrage: Levitates in the air and unleashes orange balls of Infection in all directions.

Phase 3
The third phase is announced by the Hollow knight screeching loudly yet again. Depending on the player's progress, the fight will be interrupted by Hornet, allowing player to access its mind with the Dream Nail and fight The Radiance, otherwise the fight will continue as normal. During the thrid phase of the battle, the Hollow Knight gains one new attack on top of the old ones:
 * Failed Strike: Attempts to strike with its nail, but instead collapses on the floor, fatigued.



Tactics
The main weakness of the Hollow Knight is that they are vulnerable to attacks from above. During a Nail Lunge or Combo, jump above their head and Nail bounce a few times while they finish their attack. If they try to Parry, simply dash away before they counter-attack.

While seemingly random, during Infection Shot and Infection Barrage there is a pattern to the blobs, so pay attention and move into safe zones. Dashing can often overshoot a safe zone, so walking is usually safer.

During Engorged Slam, they will home in on the player nearly perfectly if moving in one direction, but will have trouble tracking if the player constantly changes direction. Don't run away, instead dodge the first slam, then dash under them when they rise for a new slam, then reverse again after they come down and repeat.

During Infection Pillars, the pillars will briefly charge on the floor before erupting, showing where it's safe to stand. When the Hollow Knight jumps and readies their Nail, start looking for a safe zone immediately after dodging the downward strike.

The Hollow Knight's Teleport will usually position them far away from the player, so using Vengeful Spirit/Shade Soul during this time is useful to get hits in before they charge another attack. Moving too far from the Hollow Knight makes them more likely to teleport close to the player, so be careful running away to heal.

Under normal circumstances, the Hollow Knight is immune to the Dream Nail and will not grant any SOUL on a successful hit.

Depending on the player's progress, one of the three endings will play out after the fight. After the ending, the player will spawn at the last Bench rested at.

Note: The Dream Nail dialogue was extracted from game files and is not visible in-game, as the Hollow Knight is normally immune to standard Dream Nail hits.

Trivia

 * It is unknown as to why the Hollow Knight begins to stab themselves halfway through the fight. It could be trying to help the player by attempting to kill themselves, or they could be trying to further increase their strength by opening up the Infection more, in an act of desparation. It could also be going mad and trying to destroy the Infection that's slowly taking it over.
 * It is explained through NPC dialogue that the Hollow Knight could not contain the Infection due to an unnoticed flaw which caused the them to not be "completely hollow."
 * It is implied that, in the first ending ("The Hollow Knight"), this will also happen to the player - they also failed to become completely hollow, and eventually the Infection will leak through once again.
 * In the Sealed Siblings ending, the player is noted by the White Lady to have become truly hollow due to acquiring the Void Heart, and thus able to fully contain the Infection. Whether this is actually true or another assumption that could be proven wrong remains unknown.
 * During the scene in The Abyss, before the player receives the Void Heart, a Vessel similar looking to the player character is shown exiting the Abyss with the The Pale King. Judging by the shape of its horns, it seems that it's the same Hollow Knight fought in the Black Egg Temple. It also looks at the player character before following the Pale King out. This also could hint towards the original not being completely hollow, as it displayed some form of sympathy or sadness.
 * It is unknown if the Hollow Knight has a second arm, as they performs most of their actions with just one arm, and never show a second arm during the battle. Their Shade, however, appears to have both arms.
 * During the ending sequence of The Radiance fight, the Hollow Knight's shade appears and opens up a weak point on The Radiance's head, allowing the player to land the finishing blows.

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