Here is the full list of all 29 Marlow Briggs and the Mask of Death achievements.
Watch all credits
Complete the game on Hardcore difficulty
Complete the game on any difficulty
Skip all cutscenes in one play through
Find all collectibles in one play through
Defeat HellHound
Kill enemy with each magic
Defeat the Air boss
Fly across the chasm
Kill enemy with each weapon
Glide for more than 6 seconds
Solve the temple puzzle
Defeat the Water boss
Gain entry to treasure room.
Execute an enemy
Solve the water puzzle
Kill enemy with air combo.
Launch enemy and kill it before it falls on ground
Perform a 50-hit combo
Survive train-cart ride
Destroy 10 enemies using only spirit knives
Kill enemy with enviromental objects (fire, barrel,...)
Defeat the Fire boss
Find a collectible
Block enemy attack.
Earn upgrade point and spend it
Kill enemy with deflected projectile
Get your first achievement
Knock enemy off ledge into their falling death