Three retired brothers, each teaching one Nail Art, who all studied under the Great Nailsage Sly and end as the gate to his basement reveal.
The Nailmasters are the only Hollow Knight NPCs who collectively gate a single secret. According to the wiki, Mato in the Howling Cliffs, Oro in Kingdom's Edge, and Sheo in Greenpath each teach one Nail Art (Cyclone Slash, Dash Slash, and Great Slash respectively), and only by learning all three does Sly's basement reveal scene as the Great Nailsage unlock.
Per the wiki, all three were pupils of the Great Nailsage Sly back when he still wielded a nail. Mato was enthusiastic but not the most skilled. Oro was reluctant. Sheo was the strongest, then walked away from the nail entirely to paint. The three trained together, then scattered to the corners of Hallownest after a falling out.
The wiki specifies that the teaching style differs by brother. Mato teaches the Cyclone Slash freely and calls the Knight his "child" after. Oro charges Geo and treats the lesson as a transaction. Sheo only relents after the Knight's disinterest in his paintings, and even then teaches the Great Slash with his brush, not a nail.
This guide covers each Nailmaster's location and lesson, the three Nail Arts they teach, the Nailmaster's Glory charm, the Brothers Oro & Mato dual fight plus Paintmaster Sheo in the Pantheons, and the Great Nailsage Sly basement scene that closes the questline.
Mato, 
Oro, and 
Sheo, three brothers who teach the Knight one Nail Art each.
Howling Cliffs, teaches Cyclone Slash for free.
Kingdom's Edge, teaches Dash Slash for a fee.
Greenpath hut, teaches Great Slash with his brush after the Knight ignores his paintings.The Nailmasters are three retired brothers, all former pupils of the Great Nailsage Sly. Per the wiki, the wiki frames them as "Legendary masters of Nail Arts who are willing to pass their knowledge to new pupils." Each lives in a different corner of Hallownest, each teaches one Nail Art, and each has a different relationship with the Knight and with his brothers.
According to the wiki, Sheo was the most skilled of the three; Oro calls him "the mightiest of the Great Nailsage's pupils, far outshining Mato and myself." Mato was the most enthusiastic teacher. Oro was the most reluctant of the three and is "haunted by something" the wiki never names.
The wiki specifies that the brothers fell out at some point and scattered. Mato and Sheo were close during training; Oro and Mato did not part on good terms, and Oro owes Mato something neither will explain. In practice, this is the human-feeling subplot most players get pulled into without realising it; the three Nail Arts are the gameplay surface, the family fallout is the lore.
Mato sits in his hut at the top of the Howling Cliffs. Per the wiki, he recognises the Knight as a fighter immediately and does not waste time on a preamble before making them his disciple. He teaches the Cyclone Slash, which spins the Knight in place while the nail traces a fast 360-degree arc.
According to the wiki, the Cyclone Slash is the most crowd-friendly Nail Art in the game. It hits in every direction, scales with nail damage like the other arts, and counts as a charged-nail strike for charm interactions. The wiki specifies that Mato teaches it for free; there is no Geo cost and no quest hoop. The fight pose at the start of the lesson is the only formality.
The wiki notes that after teaching the Cyclone Slash, Mato is "overwhelmed with emotion" and considers the Knight his "child." He invites the Knight to meditate with him on every return visit. After the Knight learns Great Slash from Sheo, Mato says, "Ah! So my brother Sheo has taught you his Nail Art, the Great Slash! How lucky you are to have trained with him!" After Dash Slash from Oro, the tone changes: "I still haven't forgotten what he owes me and I never will."
Take Mato first. Per the wiki, his lesson is free and the Howling Cliffs entrance via the Dirtmouth Stag is the lowest-friction Nail Art unlock in the game. In actual play, having Cyclone Slash before False Knight makes the room-clearing fight noticeably shorter and gives the Knight a charm-economy excuse to start running Quick Focus early.
Oro lives in a hut at the far reaches of Kingdom's Edge. Per the wiki, he is the one Nailmaster the Knight has to pay for the lesson; the wiki quotes him directly: "It is the law of the Great Nailsage that I must pass down my teachings to those who are worthy. But no law forbids me from exacting a payment for my time." The fee is in Geo, paid before the Dash Slash demonstration.
According to the wiki, Dash Slash is the most movement-friendly Nail Art. The Knight charges the move and then dashes forward in a single committed strike, which functions as both damage and re-positioning. The wiki notes the Knight can phase through enemies during the active dash frames, which is the in-fiction reason Oro's art is the speedrunner pick.
The wiki specifies that Oro is "haunted by something" he never explains. He sends the Knight away after the lesson with a one-line dismissal: "Go back into the world, traveller, and leave me to my solitude." After a few runs, this is the most off-putting Nailmaster interaction in the game; he is the only one who does not invite the Knight back. The fallout with Mato remains unresolved across every visit.
Sheo sits in his hut in Greenpath, painting a bug shell. Per the wiki, he is the most skilled of the three brothers, and the one who walked the furthest from the nail. The wiki quotes him directly: "The only thing that drove me was becoming stronger and honing my skills with a nail," but that drive faded.
According to the wiki, the Knight's disinterest in Sheo's paintings is what triggers the lesson. He concedes and teaches the Great Slash, the heaviest and slowest of the three Nail Arts. The wiki specifies that he uses his paint brush for the lesson, not a nail, "explaining that it is the same as a nail to him."
The wiki notes that Sheo invites the Knight to stay and paint with him on return visits. He recognises when the Knight learns the other two Nail Arts, and he is the NPC who takes notice when the Great Nailsage Sly acknowledges the Knight as Nailmaster. The acknowledgement moves him, but the wiki specifies it is not enough to pull him back to the nail.
The Nailmaster's Glory charm is the gameplay tie-back to the questline. Per the wiki, learning all three Nail Arts is the prerequisite to receiving the Charm from Sly in the basement scene. The Charm costs one Notch and halves the charge time of all three Nail Arts.
According to the wiki, the Charm is what turns Nail Arts from "situational" to "build-relevant." Without it, the charge time keeps the Knight static long enough that most boss windows close before a Nail Art lands. With it, the Cyclone Slash window opens up enough that the Knight can interleave a charged hit between every nail combo, which scales aggressively with charm-based nail buffs.
The wiki notes that the Charm is the cleanest in-game confirmation that Sly is the Great Nailsage. He hands it over himself, calls the Knight "warrior" for the first time, and says, "Now tradition decrees you too may hold the symbol." The symbol is the charm.
Slot Nailmaster's Glory with Quick Slash and Mark of Pride for the strongest mid-game nail build. Per the wiki, the charge-time reduction lets Great Slash open boss-stagger windows on a much shorter cycle. In actual play, this is the recommended loadout for the Brothers Oro & Mato Godhome fight, where their own dash patterns punish stand-still casting.
The Godmaster DLC turns the Nailmasters into bosses. Per the wiki, all three appear in the Pantheon of the Sage. Brothers Oro & Mato fight together as a dual encounter, and Paintmaster Sheo fights solo as the slowest, heaviest nail combat in the Pantheon.
According to the wiki, the Brothers fight uses both brothers' signature Nail Arts: Oro's Dash Slash and Mato's Cyclone Slash, often layered together. The wiki notes that Mato performs his signature Cyclone Slash while Oro replaces his with Dash Slash, so the two cover different angles on each pass. The fight punishes standing still in the middle of the arena.
The wiki specifies that Paintmaster Sheo is the slowest and heaviest Nailmaster boss, with Great Slash chains and paint-based projectile attacks. He is generally rated tougher than the Brothers because of the windup time on his strikes, which baits late dashes. In real runs, Nailmaster's Glory plus Quick Slash is the standard prep because it shrinks the trade window.
The Nailmasters tie into the Nail Arts mechanics, the Great Nailsage Sly reveal, and the Godmaster Pantheon. These spokes pick up the connected threads.
Game data and screenshots adapted from hollowknight.fandom.com, used under CC BY-SA 3.0. Original content remains the property of the wiki contributors and Team Cherry.