Full list of all 23 Absinthia achievements.
The base game contains 18 achievements, and there are 2 DLC packs containing 5 achievements.
Defeat Lilith.
Defeat Contesse.
Defeat the Dirge of Sorrow.
Complete the Umbralair.
Defeat Marcos and co. at Sunderville.
Defeat Methuselah.
Defeat the Dragonox.
Complete Morgoth's Lair.
Defeat an Apollyon.
Emerge victorious in all four bouts in the arena.
Defeat the final boss.
Defeat the final boss on Hard difficulty.
Become the Spittoon Master.
Return Isaac's Soul Gem to Grace.
Defeat the Gargolax.
Fulfill The Iron Chef's requests.
Defeat Ibuki.
Discover 10 secret areas.
Rematch and defeat Ibuki five times.
Defeat Cleocatra five times.
Defeat the final boss on Master difficulty.
Defeat the leader of the Drakonites.
Solve the optional puzzle in Typh.