Here is the full list of all 22 Witch Explorer achievements.
Start the game
Finish the tutorial
Clear all forest stages
Clear all cave stages
Clear all abyss stages
Defeat the final enemy
Defeat the Ent
Defeat the Sentinel
Defeat the Mother Seed
Defeat the Revanant
Defeat the Youngest Siren
Defeat the Elder Siren
Defeat the Eldest Siren
Enhance the Sylph to the maximum
Enhance the Salamander to the maximum
Enhance the Fenrir to the maximum
Enhance the Volt to the maximum
Enhance the Undine to the maximum
Enhance the Shade to the maximum
Enhance the Sprite to the maximum
Enhance the dish to the maximum
Take back all facilities