Here is the full list of all 20 Heaven vs Hell achievements.
Buy your first unit
Defeat 5 Enemies
Defeat 15 Enemies
Defeat 50 Enemies
Defeat 100 Enemies
Defeat 200 Enemies
Defeat 300 Enemies
Defeat 500 Enemies
Defeat 750 Enemies
Defeat 1000 Enemies
Open first spell in Magic Book
Find your first artifact
Open Dungeon
Win battle in less than 5 seconds
Complete Angel's campaign
Complete Demon's campaign
Summon 10 zombies as Necromant
Heal your units on 3000 health using Healer Maid
Suck blood on 500 health using Vampire
Put to sleep your enemy 50 times with Buddha