Xero

Sero is a Warrior Dream boss in Hollow Knight.

Lore
Xero was a warrior of Hallownest who believed that strength would always allow him a bright future. When his mind was infected, he hoped to fight against the plague with violence. Fueled by the same hope, he turned against the Pale King, for which he was executed. Xero was buried in the Resting Grounds, his tomb a reminder to any who would betray the King. When his ghost awaken, he still could not see the wrongness of his actions and believed instead his demise to be the result of a doomed fate.

Hollow Knight
Xero's ghost appears to the Knight once they have acquired the Dream Nail. He accepts their challenge to mock his own fate. Once defeated, Xero finally acknowledges that his action against the King were irrational. The ghost confides to the Knight its faith in their bravery, before shattering in 100 Essence to be collected by the Dream Nail.

Behaviour and Tactics
Xero only has one attack:


 * Nail Cast: Xero will spawn in 2 glowing Nails. While floating around he will constantly shoot out one of his nails in the Knight's direction and will draw it back. He will shoot a Nail every 1-2 seconds. Coming into contact with the nail while it's being drawn back still can deal damage. At 50% hp Xero will spawn 2 more Nails and his attack pace will increase to 0.75 seconds between each Nail Cast.

If the player stands slightly away from Xero when they fire their nail, then dashes to directly below them in the first phase, the nail can be easily avoided.

The player can heal easily by running off the platform and to the far left of the area, where Xero's attacks will not reach, or by running under the platform. Note that this is not possible when fought in Godhome.



Trivia

 * His grave message used to read "Here lies a Traitor", which was changed to the current message after the public release version 1.0.2.8.

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