Here is the full list of all 149 Nightmare Reaper achievements.
Obtain 500 horse waters
Obtain 500 Vs
Obtain 500 nightmare reapers
Complete 405 levels with pills
Obtain 500 reflections
Complete 250 random events
Reach New game+ 3
Complete a level with 250 toxicity
Change a stat to +2 attack
Obtain 10000 headshot kills
Reach round 100 in an arena
Complete 135 levels with pills
Obtain 10000 treasures
Reach New game+ 2
Get the sacrifice ending
Reach round 50 in an arena
50 high falls into water
Obtain 1000000 jade
Complete a level with 100 toxicity
Reach bynnyhop max speed
Complete 45 levels with pills
Buy 180 jade upgrades
Unlock all pet skills
Break 10000 clutter objects
Lose 2000 life as blood ammo
Have 2 pets
Have a pet with 2 skills
Buy 100 jade upgrades
Unlock all pets
Buy 50 jade upgrades
Complete a level with 20 toxicity
Sell a weapon for 1000000
Obtain 240000 jade
Unlock 8 arenas
Reach New game+ 1
Find everything in the hospital
Complete buried ruins
Get the control ending
Complete the flesh pits
Complete blood and brimstone
Complete sorcerer's mansion
Complete the empty
Complete 75 random events
Complete 15 levels with pills
Complete 5 levels with pills
Obtain 20 horse waters
Obtain 20 reflections
Pickup a weapon after death
Get all bonuses in a level
Obtain 20 nightmare reapers
Douse yourself 50 times
Obtain 20 Vs
Start a level with no weapon
Change a stat to blood ammo
Do 20 rocket jumps
Complete crushing depths
Buy 10 jade upgrades
Buy all skills from world 8
Complete the wasteland
Complete moon terror
Kill 5000 enemies
Complete fields of death
Buy 125 skills from the tree
Burn freeze and shock an enemy
Buy all skills from world 7
Complete gibbs medical center
Have a carried barrel explode
Sell 500 weapons
Buy all skills from world 6
Buy 100 skills from the tree
Buy all skills from world 5
Buy all skills from world 3
Complete void beneath
Unlock 5 arenas
Complete boulder penitentiary
Complete vermilion princess
Buy 75 skills from the tree
Complete murky docks
Complete rust works
Complete gardens of woe
Get all secrets in a level
Buy all skills from world 4
Complete carnage way
Obtain 1000 headshot kills
Obtain 5 Vs
Complete tower of toil
Kick 50 enemies to death
Buy 50 skills from the tree
Obtain 1000000 gold
Break 2500 clutter objects
Obtain 1000 treasures
complete the descent
Kick a boss
Accept 5 merchant offers
Buy all skills from world 2
Complete gloom mansion
Get all treasures in a level
Reach round 10 in an arena
Obtain a 35x combo
Obtain 60000 jade
Obtain 5 reflections
Obtain 20000 jade
Unlock 2 arenas
Complete putrid sewers
Complete drudge village
Buy 25 skills from the tree
Complete disavowed town
Buy all skills from world 1
Obtain a 25x combo
Complete sulfuric mines
Complete 15 random events
Obtain 5 nightmare reapers
Obtain a legendary weapon
Obtain 150000 gold
Buy 10 skills from the tree
Obtain 5 horse waters
Complete forsaken village
Complete immemorial woods
Kill 500 enemies
Sell 50 weapons
Obtain V
Obtain a 15x combo
Break 250 clutter objects
Complete spore pit
Obtain 100 treasures
Obtain 50000 gold
Obtain 100 headshot kills
Obtain reflection
Complete hollow stone
Sell 25 weapons
get all kills in a level
Complete 5 random events
Obtain horse water
Wake up prematurely
Kill 3 enemies with one bullet
Break 100 clutter objects
Sell 10 weapons
Buy a skill from the tree
Kill 100 enemies
Obtain 20 treasures
Obtain a level 3 weapon
Obtain 20 headshot kills
Obtain 10000 gold
Obtain a rare weapon
Obtain nightmare reaper
Obtain an uncommon weapon
Kill 30 enemies
Obtain a 5x combo
Obtain a level 2 weapon