Here is the full list of all 24 Nadir: A Grimdark Deckbuilder achievements.
Unlock Hernan Cortes as a playable character
Defeat Moloch
Earn any Desires for the first time
Defeat Koschei the Immortal
Earn any Idols for the first time
Defeat Feaster from Afar
Defeat Abaddon
Obtain any Rare card
Unlock Vlad Tepes as a playable character
Defeat the Gunnery Demon
Defeat Fury
Earn any Skulls for the first time
Defeat Beelzebub
Earn any Relics for the first time
Defeat Belzebub
Possess a Damned as a reward
Purchase any card in the shop
Earn any Filth for the first time
Play the Saint's Blood card
Defeat Lilith
Defeat Minos
Defeat Chernobog
Defeat King in Yellow
Defeat Asmodeus