Pretty easy. Just mix three types of ingredients. All of them are found on the table; there are no other ingredients.

⭐📜Wizard Apprentice
Brew 6 spells in the cauldron.

⭐📜Wizard Master
Brew all 12 spells in the cauldron.

• 📜Magnetize
  
• 📜Miniturize
  
• 📜Supersize
  
• 📜Polymorph
  
• 📜Transmute
  
• 📜Conductor
  
• 📜Puppeteer
  
• 📜Fireworks
  
• 📜Air Drawing
  
• 📜Fireball
  
• 📜Weightless
  
• 📜Symphony

Grab the ear trumpet beside Skelly, equip it, and search the entire room. Follow the whispers; you should eventually find ten artifacts.

⭐📜Artifact Connoisseur
Find five whispering artifacts.

⭐📜Artifact Seeker
Find ten whispering artifacts.

⭐📜Sword Master

• Win the fruit-slicing minigame.
  
• Pick up the light saber and stand right in front of the gargoyle (to the right of the cauldron table). That should slice every fruit thrown at you.

⭐📜Crossbow Master

• Win the target minigame.
  
• You can easily do this. It's located near the window face the window, below the clock.

⭐📜Scavenger Hunt

• Finish the scavenger hunt
  
• Lighttbulb made a short guide for this.

📜Bullseye!

• Play darts and hit the center of the dartboard.
  
• The game is near the entrance of the courtyard, along the walls. You can easily hit the center by standing near the pathway. It won't work if you're too close.

📜Three in one!

• Make a ball pass through all three hoops at once.
  
• Make yourself larger (voice cast, "make me larger") so you can aim directly at the three hoops.

📜It's all in the hips

• Play golf.
  
• Or just carry the golf ball and drop it in the hole

⭐📜 Afraid of heights

• Visit the canyon bridge.
  
• Green (C) → Blue (G) → Grey (C+) → Blue (G) → Green (C)

⭐📜Aggh, a monster!

• Encounter the "monster."
  
• Yellow (F) → Orange (A) → Red (E) → Blue (G) → Yellow (F)
  
• Don't worry; there are no jumpscares (at least at the time of writing).

⭐📜Master of the Maze

• Complete the maze trial.
  
• Red (E) → Orange (A) → Blue (G) → Yellow (F) → Grey (C+)
  
• Equip "Q → Electric". That's the only offensive spell you'll need.
  
• For the bridge, activate the first and final buttons, then jump the gap.
  
• Kneel (crouch) at the artifact at the end to get the achievement.
  
• NOTE: you must achieve this before you can get the next achievement.

⭐📜Judgement

• Put on trial by the interdimensional judges.
  
• Purple (D) → Grey (C+) → Purple (D) → Turquoise (H) → Purple (D)
  
• Move around, play with the tools
  
• Grab time cylinder →📜Caught somewhere in time (requires Master of the Maze)

⭐📜Ooh, a secret!

• Play the hidden musical notes.
  
• Orange (A) → Yellow (F) → Green (C) → Red (E)
  
• Grab the ring inside the wall, opposite the skeleton →📜Precious
  
  • Make yourself larger or smaller if you can't see the hole.

⭐📜Why did I drink that?

• Drink the 3 hidden potions.
  
• There's one under the cauldron, one on the table beside the window, and one on the shelf beside the exit (the shelf behind the broom).

⭐📜Aaaaaaahhhh!

• Throw Skully out the window.

⭐📜Catch this!

• Play catch with the armor knight. Toss him anything.

⭐📜UNLIMITED POWER!

• Electrify Skully 25 times.
  
• There are times when the sticker unlocks but not the achievement. When that happens, remove everything, restart the room, and do it again.

📜Blrgrlglgl

• Drown Skully in the pot.

📜Down he goes…

• A person sometimes climbs out of the basement (no jumpscares; don't worry). Hit him with something.

📜Right in the eye

• A giant sometimes peeks inside the Tower. Hit him in the eye.

📜Ten thousand years…

• Rub the magic lamp. It's located at the shelf behind the broom.

📜Waste allocation load lifter

• Put several items into the trash can.
  
• Voice cast "create trash" to make things easier.

📜Spreading the love

• Blow the dandelion
  
• It's at the bottom of the statue beside the door. Grab it, hold it close (like charging up for a throw), then blow on your mic.

📜Good intentions

• There's a person in the well. Help him climb.
  
• You should find the crank on the shelf, in front of the table, beside the red ball. Orient it correctly and use it on the well.

📜The power of voice

• Find the voice ring. It's at the courtyard. Skully will lead you to it.

📜You can call me…

• Ask Skully's name

📜Inquisitive mind

• Ask Skully, "what is this?"

⭐📜Vocal Virtuoso
Use all unique voice commands.

• 📜Bouncy
  "Make this bouncy."
  
• 📜Explode
  "Make this explode"
  
• 📜Glue
  "Glue these together."
  
• 📜Gravity
  "Make gravity light."
  
• 📜Jump
  "Make this jump."
  
• 📜Pin
  "Pin this"
  
• 📜Pitch
  *point at Skully* "Make him sound tiny."
  
• 📜Size
  "Make me huge."
  
• 📜Time
  "Make time slower."

You'll get these as you climb up the fortress.

⭐📜Arcane Artisan
Use all Natural Magic powers.

• 📜Lightning
  
• 📜Neutron Blast
  
• 📜Neutron Orb
  
• 📜Spectral Orb
  
• 📜Spectral Scream
  
• 📜Tornado

Climbing
Voice cast "make me fast", then voice cast "if I snap, make everything explode", then equip "Q → snap". You'll plow through the fortress.

⭐📜So much left to know
Finish the first 10 levels in the Observer Fortress.
⭐📜The fall explained
Finish the first 25 levels in the Observer Fortress.
⭐📜The truth revealed
Finish all the levels in the Observer Fortress.

Eliminating
If it couldn't be summoned, voice cast "summon ten drones/automatons" instead. It'll eventually appear after a cast or two.

⭐Conqueror of Chaos
Defeat all the unique Observer Fortress enemies.

• 📜Stone Automaton
  voice cast, "summon an automaton"
  
• 📜Blaster Automaton
  can't specifically summon via voice cast, as far as I know.
  
• 📜Demolisher Automaton
  haven't tried summoning because the game kept hearing "demolisher" as "demolish her" or "the militia"
  
• 📜Elite Automaton
  "summon an elite automaton"
  
• 📜Giant Automaton
  "summon a giant automaton"
  
• 📜Larvops
  "summon drone"
  
• 📜Larvops Grenadier
  can't specifically summon via voice cast, as far as I know.
  
• 📜Elite Larvops
  "summon elite drone"
  
• 📜Vessel
  "summon a vessel". can't be defeated by OP snap spell. Use "natural magic: lightning" instead

⭐📜Coven of Cooperation

• Use the Co-Op mode.
  
• Go find friends, lmao.
  
• There are three ways to activate it: in the main menu, F1 keyboard key, Start button of a controller.