Here is the full list of all 50 Blackfaun achievements.
Defeat 200 enemies
Complete the game on any difficulty with Eri
Defeat 30 Succubi in the Court of Thorns
Defeat 100 Dreamsnatchers in the Lyrewood Vale
Die for the first time
Use 150 candles
Use your Mana Burst on 50 enemies
Defeat Censha, the Red Spear for the first time
Defeat Ugark, the Thunderous Hoof 5 times
Defeat the Relic Guardian 4 times
Defeat Mosh, the Crackling Blade 3 times
Defeat Elora, Vileweed Monarch in the Lyrewood Vale for the first time
Defeat Braald, the Wolflord 5 times
Complete the Lyrewood Vale without taking magic damage
Defeat 100 enemies with your familiar
Achieve a movespeed stat of 100 or greater
Defeat 50 Glinteye Rogues in the Temple Depths
Defeat 80 Wraiths in the Duskhaven Sanctuary
Complete a level without attacking
Defeat 250 champion monsters
Collect 15 talismans
Collect 1000 wisps
Defeat 50 enemies in the Temple Depths while slowed by an Ickwater Mystic
Destroy 20 turrets in a single Stonebeak, Hydra Baron boss battle
Collect 100 or more gold in a single level
Complete the game without buying anything from the merchant on normal or higher difficulty
Use your Mana Burst to successfully exploit all 16 boss's weaknesses
Sprint for a total of 40 seconds
Defeat Moonfeather, the Last Hippogryph 20 times
Complete the game 30 times on normal or higher difficulty
Achieve a shot size stat of 200 or greater
Defeat 200 enemies that are affected by frenzy
Lose 3000 or more health in a single playthrough
Complete Duskhaven Sanctuary without defeating any spirit elks
Reduce any stat to -100 or less
Complete the game on normal or higher difficulty without equipping a flawless or fabled item
Discover 150 secret rooms
Complete the game as Pan on Hard difficulty
Equip 100 fabled items
Candle-dodge 8 lasers in a single Mosh, the Crackling Blade boss battle
Buy 50 items from the merchant
Defeat Aleog, Rider of Wonder without taking damage
Defeat 10000 enemies
Complete Duskhaven Sanctuary in under 12 minutes
Defeat Eri on normal or higher difficulty without taking damage
Complete the game on normal or higher difficulty with 3/5 equipment slots used
Defeat 200 enemies in a row without taking red health damage
Achieve a hit that deals 2500 damage or more
Achieve a shot range stat of 450 or greater
Finish the game on normal or higher dificulty with an accuracy of 80% or greater