Nail

Nail is the term used to describe the bladed weapons wielded by several enemies, NPCs, and bosses in Hollow Knight, including the Knight.

The Nailsmith in the City of Tears can upgrade the Knight's Nail up to 4 times if given enough Geo and Pale Ore, which increase the damage of Nail strikes.

The Fragile Strength/ Unbreakable Strength and Fury of the Fallen Charms also increase Nail damage.

Nail Upgrades

Nail-bouncing By jumping and slashing down with the Nail on environment jugs, spikes, or enemies, the Knight can bounce. This move, known as "Nail-bouncing" or "pogo-jumping." It is useful for fighting enemies and platforming.

in the southeastern region of the Forgotten Crossroads you will find a Grub that is on a ledge surrounded by spike platforms. To get it without the need to use Monarch Wings and Mothwing Cloak you can alternatively Nail-bounce to jump across.

In the Fungal Wastes, there are pink mushrooms on which the Knight can Nail-bounce to bounce higher than usual. They must be used as a platform to access the Mantis Village a Grub and other locations before obtaining the Mantis Claw, Monarch Wings, or Isma's Tear.

Aside from these mushrooms, there are a few other times where Nail-bouncing is required:
 * To obtain a Vessel Fragment in Deepnest by Nail-bouncing on Garpedes.
 * To complete some parts of the White Palace and the Path of Pain.

Trivia
 * Upgrading the Nail does not change its appearance in the Knight's sprites.

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