Here is the full list of all 21 Necromancer Returns achievements.
Spend 10000 gold.
Deal 5000 of magical damage.
Put artifacts on the hero.
Summon 5 skeletons.
Win 20 battles.
Deal 15000 of physical damage.
Lose 2000 of health.
Deal 5000 of physical damage.
Spend 200 of mana.
Win in 5 battles.
Complete Tutorial.
Win 40 battles.
Heal 1000 of health.
Resurrect after death.
Use Vampirism spell 5 times.
Use units’ abilities 20 times.
Learn all skills.
Upgrade all units.
Complete all quests.
Complete campaign mode.
Win in 5 battles in the mode of "Survival"