• Falsehood
  The False Knight - fought in the Forgotten Crossroads at the very beginning.
  
  
  
  
• Strength
  The Failed Champion - dream version of the False Knight. Entry to the fight is behind a secret wall in the False Knight's arena.
  You need the Dream Nail to fight this boss.
  
  
  
• Test of Resolve
  Hornet - fought in Greenpath.
  
  
  
  
• Proof of Resolve
  Hornet, again - fought in Kingdom's Edge.
  
  
  
  
• Respect
  The Mantis Lords - fought at the bottom of the Fungal Wastes/Mantis Village.
  
  
  
  
• Illumination
  The Soul Master - fought in the Soul Sanctum at the top of the City of Tears.
  
  
  
  
• Mortality
  Dream version of the Soul Master.
  You need the Dream Nail to fight this boss.
  
  
  
  
• Honour
  Dung Defender - fought in the Royal Waterways.
  
  
  
  
• Release
  The Broken Vessel - fought in the left end of the Ancient Basin.
  
  
  
  
• Peace
  The Lost Kin - dream version of the Broken Vessel.
  You need the Dream Nail to fight this boss.
  
  
  
  
• Obsession
  The Collector - fought at the top of the Tower of Love.
  
  
  
  
• Rivalry
  Zote the Mighty - fought during the first round of the colosseum of fools.
  
  
  
  
• Execution
  The Traitor Lord - fought at the top left of the Queen's Gardens.
  
  
  
  
• Beast
  Herrah the Beast, found in Beast's Den at the left end of Deepnest.
  No fight, just attack her a few times.
  You need the Dream Nail to fight this boss.
  
  
  
• Teacher
  Monomon the Teacher, found in Teacher's Archives in the middle of Fog Canyon.
  No fight, just attack her a few times.
  You need the Dream Nail to fight this boss.
  
  
  
• Watcher
  Lurien the Watcher, found in Watcher's Spire atop the City of Tears.
  No fight, just attack him a few times.
  You need the Dream Nail to fight this boss.

If you need help with any boss, this guide by wataniyob will help you out:
https://steamproxy.net/sharedfiles/filedetails/?id=889617082

• Charmed
  Get any charm.
  
  
  
  
• Enchanted
  Get half of Hallownest's charms.
  
  
  
  
• Blessed
  Get all of Hallownest's charms - then, return to Salubra and buy her Blessing.

The following guide by Icarus tells you where all charms are located:
https://steamproxy.net/sharedfiles/filedetails/?id=1351842389

If the location descriptions in the guide are not enough for you, you can use this guide by AlexanderXIII to see where exactly your missing charms are:
https://steamproxy.net/sharedfiles/filedetails/?id=874455821

• Warrior
  Beat the colosseum's first trial.
  
  
  
  
• Conqueror
  Beat the colosseum's second trial.
  
  
  
  
• Fool
  Beat the colosseum's third trial.
  
  
  
  I can't really help you on how to do this, I can only give you some tips:
  
  
  • If you're having trouble, wait until you're in the late game and have the Shade Cloak, all three spells upgraded and a nail+3.
    
    
  • Round 2 gives a piece of pale ore, so you can upgrade to a nail+4 before going for round 3.
    
    
  • Remember that you have a Shade Cloak and can dash through enemies. You can dash through Aspid shots, you can dash through any flying enemies on the 'no ground' parts.
    
    
  • You can instantly kill Primal Aspids, red hornets and flying mantis traitors with a Great Slash or Dash Slash (with a nail+3 at minimum). You can also charge nail arts while sliding on a wall, which is great for 'no ground' parts. Nailmaster's Glory is heavily recommended.
    
    
  • You can keep bouncing on the green flying enemies or keep attacking them from below so they cannot attack you.
    
    
  • Shade Soul combined with Shaman Stone deals tons of damage and is great to clear whole waves at once.
    
    
  • I used Quick Slash, Quick Focus, Shaman Stone, Nailmaster's Glory to easily get through it. You can also experiment with Sharp Shadow, Dashmaster (a shade dash downwards can often save you), Longnail/Pride, Shape of Unn, Spell Twister.
    
    
  • If you can manage to stay at full health, Grubberfly's Elegy is really stong.
    
    
  • If you're doing this on a Steel Soul run, remember that you can use fragile charms with no added risk. Fragile Strength is a really strong charm.
    
    
  • During any rounds with explosive birds and during the round with tons of spiders and spikes, you can just keep walljumping in the upper left or upper right corner of the arena and everything should kill itself eventually.
    
    
  • God Eater, the boss of the third round, gives up if you kill her pet, so try to focus it down. Her attacks are slow anyway so you can easily avoid her.
    
    
  • I have not tested this myself, but the game allows you to bounce on spikes with downward attacks - this probably works on the arena spikes too (when they block the ground), in case you do fall down during the 'no ground' parts.

• Cartographer
  Buy all of Cornifer's maps. He's pretty easy to find due to a paper trail and his humming leading to him. Even if you miss him in an area, you can go back to Dirthmouth and purchase the map you missed from Cornifer's wife.
  
  
• Completion
  Achieve 100% completion and finish the game.
  
  
  
  
• Pure Completion
  Achieve 112% completion and finish the game.
  
  
  
  
  The things that count for 100% completion in the base game are:
  
  
  • All four nail upgrades: 1% each
    
  • The Dream Nail : 1%
    
  • The Awakened Dream Nail: 1%
    
  • The four mask upgrades: 1% each
    
  • The three soul vessel upgrades: 1% each
    
  • The Kingsbrand: 2%
    
  • The Crystal Heart: 2%
    
  • The Mantis Claw: 2%
    
  • The Monarch Wings: 2%
    
  • Isma's Tear: 2%
    
  • The Mothwing Cloak: 2%
    
  • The Shade Cloak: 2%
    
  • Vengeful Spirit, Howling Wraiths, Desolate Dive: 1% each
    
  • Shade Soul, Abyss Shriek, Descending Dark: 1% each
    
  • The three nail arts: 1% each
    
    
  • Herrah the Beast, Monomon the Teacher, Lurien the Watcher: 1% each
    
  • Galien, Marmu, Markoth, Xero, No Eyes, Elder Hu, Gorb: 1% each
    
  • Brooding Mawlek: 1%
    
  • Gruz Mother: 1%
    
  • The Collector: 1%
    
  • Uumuu: 1%
    
  • Nosk: 1%
    
  • The Traitor Lord: 1%
    
  • The Broken Vessel: 1%
    
  • The Watcher Knights: 1%
    
  • The Dung Defender: 1%
    
  • The Soul Master: 1%
    
  • The Mantis Lords: 1%
    
  • Both Hornet fights: 1% each
    
  • The False Knight: 1%
    
  • The three colosseum battles: 1% each
    
    
  • 36 charms: 1% each
    
    
  • The Seer's final words when showing her 2400 essence: 1%
  
  Once the three dreamers are defeated, you can enter the Black Egg Temple. Next to the Black Egg Temple's bench is a stone you can interact with - doing so will allow you to see your completion percentage in the menu and inventory.
  Once you have 100%, fight the final boss. The achievement unlocks after the credits.
  
  The Grimm Troupe update added another 6% game completion:
  
  
  • Four new charms: 4%
    
  • Grimm, fought in Dirtmouth: 1%
    
  • Nightmare King Grimm, fought in Dirtmouth (or banishment of the Grimm Troupe): 1%
  
  
  The Lifeblood update added another 1% game completion:
  
  
  • Hive Knight, fought in The Hive at the Hive Queen's location: 1%
  
  The Godmaster update added another 5% game completion:
  
  
  • Unlocking the Godtuner: 1%
    
  • Pantheon of the Master: 1%
    
  • Pantheon of the Artist: 1%
    
  • Pantheon of the Sage: 1%
    
  • Pantheon of the Knight: 1%
  
  
• Steel Soul
  Finish the game in Steel Soul mode. If you want to scum the achievement, you can quit to menu and will reset to the last bench you rested at if you're about to die.
  Since you're not allowed to die, I recommend using the Fragile Charms as they cannot break.
  
  
• Steel Heart
  Finish the game on Steel Soul mode with 100% completion. You need to do exactly what you have to do for the Completion achievement, but not die in the process. The hardest part is probably the colosseum. Good luck!
  
  
• Void
  This is the achievement for finishing the 40th charm, the Void Heart.
  You will need the Shade Cloak and 1800 dream essence to unlock this.
  
  First, go to the top left part of Queen's Gardens and past the void gate. Fight the Traitor Lord and proceed to the White Lady's place. She will give you the first half of Kingsoul, the final charm.
  
  Next, go to Palace Grounds in Ancient Basin and hit the white armour with your Awakened Dream Nail. This will not work with the Dream Nail - it has to be upgraded.
  You will be teleported to the White Palace - a platforming challenge. Use both Hiveblood and Grubsong so you cannot die in this place - it makes it easier. Once you're at the end, whack the Pale King a few times and pick up the second part of Kingsoul.
  
  Now, equip Kingsoul and go to the bottom of the Abyss. A new path will be accessible by stomping it. Navigate through the maze until you find your reflection. Use your Dream Nail on it to change your Kingsoul to the Void Heart. This charm needs no notches and cannot be unequipped. Unlocking it unlocks the achievement.
  Caution: The game has three endings. Finishing the Void Heart blocks you from accessing the first ending, but allows you to get the other two endings.

• Attunement
  Collect 600 essence.
  
  
  
  
• Awakening
  Collect 1800 essence and talk to the Seer.
  
  
  
  
• Ascension
  Collect 2400 essence and talk to the Seer one final time.
  
  
  
  Essence values:
  
  • Lost Kin - 400
    
  • Soul Tyrant - 300
    
  • Failed Champion - 300
    
    
  • Markoth - 250
    
  • No Eyes - 200
    
  • Galien - 200
    
  • Marmu - 150
    
  • Elder Hu - 100
    
  • Gorb - 100
    
  • Xero - 100
  
  This adds up to 2100. You need 300 more from essence trees and ghosts. Note that you will never need more than 2400 essence, meaning that you do not need to find every single whispering root.
  
  Whispering roots can be found at:
  
  
  • Kingdom's Edge's climb
    
  • Big, open area in the Howling Cliffs
    
  • In the wide room in Deepnest, right of Beast's Den
    
  • In Greenpath, when going there from Queen's Gardens
    
  • In the Ancestral Mound, where you unlock Vengeful Spirit
    
  • In the destroyed elevator between Ancient Basin and the City of Tears
    
  • In the Spirit's Glade in the Resting Grounds
    
  • At the bottom right part of Queen's Gardens
    
  • In the Forgotten Crossroads, at the top of the room right of the grub room
    
  • In the room below the City Storeroom stag station
    
  • At the top right of Crystal Peak
    
  • In the Resting Grounds, outside of the Seer's room
    
  • In the room connecting the Fungal Wastes and Fog Canyon
    
  • In the Hive
    

• The Hollow Knight
  You get this achievement for defeating the Hollow Knight without having the Void Heart equipped. Just fight the Hollow knight once you unlock the doors to the Black Egg Temple - the fight is pretty easy. Keep bouncing on his head with downward slashes. If he parries, bounce and dash in the direction he's looking so you can keep bouncing on his head with ease. Once he starts stabbing himself, spam attacks. If he rests on the ground, you have enough time to heal two times.
  
  
• Sealed Siblings
  Defeat the Hollow Knight with the Void Heart equipped. Once Hornet interrupts the fight, keep attacking the Hollow Knight to kill him.
  
  
  
• Dream No More
  Defeat the Hollow Knight with the Void Heart equipped. Once Hornet interrupts the fight, use your Dream Nail on the Hollow Knight to enter the final boss fight against the Radiance.
  
  
  
• Passing of the Age
  This achievement is unlocked by finishing the Mr. Mushroom secret and unlocking a post-credits scene.
  Mr. Mushroom needs to be found and talked to (with the Spore Shroom charm equipped) seven times, in this order. The trigger for him spawning should be finding all three dreamers.
  
  Mr. Mushroom locations:
  
  • Go right and down from Queen's Station.
    
  • In Kingdom's Edge, in the long room left of the Hive.
    
  • In Deepnest, at Galien's grave.
    
  • In the Howling Cliffs, at Nailmaster Mato's place.
    
  • Between the Broken Vessel's arena and the location of the Monarch Wings.
    
  • At the left end of the Fog Canyon, below the Overgrown Mound.
    
  • At the bottom of the long drop in the Howling Cliffs, where your journey started.

You are not locked out of your save file if you complete an ending. Once you complete an ending and reopen your save file, you will be placed at the bench you last rested before the fight. This means that you can get all three endings in one run.

• Grubfriend
  Find half of the imprisoned grubs.
  
  
  
  
• Metamorphosis
  Find all 46 imprisoned grubs.

After finding the Love Key in the bottom right of the Queen's Gardens, enter the Tower of Love and kill the Collector. After the fight, you can pick up the Collector's Map, which will reveral the map locations of all grubs.
After returning all imprisoned grubs and receiving all rewards, return to Daddy Grub for a small bonus.

• Keen Hunter
  Unlock all basic journal entries in the Hunter's Journal.
  
  
  
  
• True Hunter
  Unlock all of the Hunter's Notes in the Hunter's Journal and receive the Hunter's Mark.

Find every enemy and boss in the game and kill them enough to receive their upgraded entry. Small enemies respawn when reentering a room, all enemies (except for bosses) respawn when resting at a bench.
Some enemies cannot be killed and need to be found in the environment and interacted with. Lumaflies, for example, are found in the Teacher's Archives.


The following guide was made by Celery and shows all entries:
http://steamproxy.net/sharedfiles/filedetails/?id=873948268

• Protected
  Find four mask shards.
  
  
  
  
• Masked
  Find all 16 mask shards.

The mask shard locations are as follows:

• Sly's store, 150 geo.
  
• Sly's store, 500 geo.
  
• Sly's store, 800 geo.
  
• Sly's store, 1500 geo.
  
• Bretta's house in Dirtmouth after rescuing her below Mantis Village.
  
• Falling from the Fungal Core in Fungal Wastes into Deepnest, left of the Mantis Village.
  
• Queen's Station.
  
• In the Hive, after smashing a wall with a big bee.
  
• From the Brooding Mawlek, a boss behind a secret wall in the left part of Forgotten Crossroads.
  
• After delivering a set amount of grubs to Grub Daddy.
  
• Above the bench in Crystal Peak, after killing the second form of the Crystal Guardian.
  
• In the left part of the Royal Waterways.
  
• From the Seer, after 1300 essence.
  
• Greenpath, in the Stone Sanctuary (where you fight No Eyes).
  
• In the Forgotten Crossroads, below the hot spring room.
  
• The Grey Mourner's request.

• Soulful
  Find three soul vessel shards.
  
  
  
  
• Worldsoul
  Find all nine soul vessel shards.

The soul vessel shard locations are as follows:

• Sly's store, 550 geo.
  
• Sly's store, 900 geo.
  
• From the seer, after 700 essence.
  
• Left of the elevator connecting the Forgotten Crossroads and City of Tears.
  
• Two rooms above King's Station.
  
• Deepnest, in the room above the tram station.
  
• In the stag nest, after unlocking all stag stations.
  
• In the Greenpath room connecting to the Queen's Gardens.
  
• In the room below the Ancient Basin's tram station, after donating 3000 geo.

• Speedrun 1
  Complete the game in less than ten hours.
  
  
  
  
• Speedrun 2
  Complete the game in less than five hours.
  
  
  
  
• Speed Completion
  Achieve 100% game completion and complete the game in less than 20 hours.

For the Speedrun 1 and 2 achievements, I recommend following this route by Blankdud:
https://steamproxy.net/sharedfiles/filedetails/?id=878193536
I personally used this route. It's far from perfect, but I managed to finish the game in about three hours using this route, meaning there is still much room for mistakes.
You also don't need any glitches for this route and get some nail upgrades, which makes it easier.

For the Speed Completion achievement, I used the same route again up to killing the Dreamers. From that point on, I collected Monarch Wings, Kingsbrand and Shade Cloak. With all abilites unlocked, I cleared after area after area (starting with Queen's Gardens to unlock the Love Key to have an easier time finding grubs).
This would be very far from a perfect route, but I managed to finish the game in about ten hours like this. You don't have to start with Queen's Gardens and can start with easier areas to unlock more mask shards/charm notches, which makes clearing other areas easier.

• Purity
  After fully upgrading your nail, talk to the Nailsmith and kill him.
  
  
  
  
• Happy Couple
  After fully upgrading your nail, talk to the Nailsmith, but do not kill him. Instead, go to Nailmaster Sheo at the left end of Greenpath, where he will be. Talk to him to unlock the achievement.
  
  
• Neglect
  When finding Zote at the top of Greenpath being eaten alive, do not rescue him from the bug. Return later to find his dead body and attack his mask, unlocking the achievement.
  
  
• Solace
  Bring the Grey Mourner's (located in right end of Resting Grounds, behind a breakable ceiling) flower to the grave in Queen's Gardens without taking damage.
  This route[i.imgur.com] by /u/asyncD on Reddit is pretty safe. I've used it two times and did not have any problems.
  Tips: If you have it, the Glowing Womb charm spawns flies that suicide on enemies. Combined with the Defender's Crest, it spawns exploding flies. This can keep you safe (have not tried myself, but heard good things). You can use fragile charms freely since you do not want to get hit anyway. For nail builds, Longnail or the Pride charm help a lot. Spell builds should also work well due to being able to attack from a distance.
  From patch .15 onward, breaking the flower saves the game, which means savescumming (alt+f4 when the flower breaks) does not work any longer. This means that you have to do this legit.
  
  
  
• Witness
  Talk to Quirrel one last time at the right end of the Blue Lake after fighting against Uumuu with him in Fog Canyon.

Notes:
You can't get Purity and Happy couple on the same save file.
If you let Zote die, you will not be able to fight him in the Arena, which means you cannot get Neglect and Rivalry on the same save file.

• Connection
  Open half of Hallownest's stag stations.
  
  
  
  
• Hope
  Open all of Hallownest's stag stations and discover the Stag Nest.

The list of stag stations is as follows:

• Dirtmouth
  
• Forgotten Crossroads, bottom right
  
• Greenpath, top left
  
• Queen's Station, between Fungal Wastes and Fog Canyon
  
• Queen's Gardens, middle
  
• City Storerooms, top left of the City of Tears
  
• King's Station, at the right part of the City of Tears
  
• Resting Grounds, right
  
• Deepnest, at the left part, next to Beast's Den.
  
• Stag Nest, after unlocking all other stag stations
  
• Hidden Station, on the right end of Palace Grounds in the Ancient Basin, behind a breakable wall

• Memory
  White Defender, fought in the Dung Defender's dream. After defeating the Dung Defender and going right, you have to smash the ground below the acid tank with Desolate Dive (or Descending Dark) to access the Dung Defender's room.
  You need the Dream Nail to fight this boss.
  
  
• Dark Romance
  (Invincible Fearless Sensual Mysterious Enchanting Vigorous Diligent Overwhelming Gorgeous Passionate Terrifying Beautiful Powerful) Grey Prince Zote, found in Bretta's house in Dirtmouth.
  Every time you beat him, he will become stronger and gain new prefixes to his name. Added to that, one of the candles in the room below Bretta's house will light up every time you defeat him. The big Zote statue will turn golden once all ten candles are lit.
  You can only fight this boss on save files where Zote was saved. You need Bretta's house and the Dream Nail unlocked to fight this boss.
  (To unlock Bretta's House, you need to talk to Bretta. To find her, you need to go Mantis Village, to the statue where you find the Dashmaster charm. From there, go left and follow the hidden path.)

• Grand Performance
  Defeat Troupe Leader Grimm. After starting the Grimm Troupe quest in the Howling Cliffs and feeding the Grimmchild enough flames, you will be able to fight him in his tent.
  
  
  
• Ritual
  Defeat Nightmare King Grimm. After defeating Troupe Leader Grimm and feeding the Grimmchild even more flames, you can enter Grimm's tent again to find him sleeping. Enter his dream to fight Nightmare King Grimm.
  
  Note: You can not get both the Ritual and Banishment achievements on the same save file, you need to choose.
  
  
  
• Banishment
  After defeating Troupe Leader Grimm, travel to the stag station in Deepnest. There will be a flame on the map next to Beast's den. Go there and receive Brumm's flame. Once you have his flame, return to the Howling Cliffs, where you began the quest, and seal the flame away.
  
  Note: You cannot get both the Ritual and Banishment achievements on the same save file, you need to choose.
  Doing this will lock you out of the Nightmare King Grimm fight on this save file. Additionally, this will also lock you out of getting the permanent versions of the three fragile charms (though this does not make a difference for achievements, it's only annoying).

Gain access to Godhome by finding the fourth Simple Key in the spectator area of the Colosseum of Fools, then travel to the Royal Waterway. Find the Junk Pit just above the entry to Flukemarm's arena and unlock the Godseeker's coffin with your simple key. You only have to beat the five pantheons and don't need any bindings enabled if you're going for achievements. You don't have to do any of the fights in the statue room, meaning that no radiant difficulty fights are required.

• Brotherhood
  Complete the first pantheon, the Pantheon of the Master, by defeating Nailmasters Oro and Mato.
  
  
  
  
• Inspiration
  Complete the second pantheon, the Pantheon of the Artist, by defeating Paintmaster Sheo.
  
  
  
  
• Focus
  Complete the third pantheon, the Pantheon of the Sage, by defeating Great Nailsage Sly.
  
  
  
  
• Soul & Shade
  Complete the fourth pantheon, the Pantheon of the Knight, by defeating the Pure Vessel.
  
  
  
  
• Embrace the Void
  Complete the fifth pantheon, the Pantheon of Hallownest, by defeating the Absolute Radiance.