Here is the full list of all 21 Envy the Dead achievements.
Heal dying injured character
Equip character with any armor
Kill stinker boss
Train character to level 4
Use conviction answer
Feed dying hungry character
Complete stage 1
Explode barrel or propane
Defeat survivors in battle
Defeat zombies in battle
Gather any supply on x8 rate
Craft turret
Kill butcher boss
Complete stage 2
Complete game
Complete stage 1 on hardcore
Complete stage 2 on hardcore
Complete game on hardcore
Survive wave 10 in survival
Survive wave 20 in survival
Survive wave 30 in survival