Here is the full list of all 45 Artifacts achievements.
Die for the first time
Slay the Fungal Giant, the hulking rot
Slay the Giant Spider, Weaver of the Riverways
Slay the Mindless Knight, the psychic husk
Slay the Ice Ghoul, spawn of the Pit
Slay the Firebold King, ruler of the Lava Barracks
Slay the Magnum Opus, greatest of all artifacts
Slay the Mushroom Wizard, oracle of poison
Slay the Lava Wyrm, beast of the magma depths
Slay the Dark Hand, manifestation of death
Slay the Sealed God, the stifled soul
Slay the Hood, the ghost of the past
Slay the Sealers, jailors of a god
Be ambushed by the Sealers and killed
Discover the Fungal Caves, Farm for the Kingdom
Discover the Riverways, infested with spiders
Discover the Firebold Keep, or Lava Barracks
Discover the Fungal Growths, heart of the infestation
Discover the Sealer's Temple, a divine jail
Discover the Pit, basin of death
Discover the Golem Workshop, littered with husks
Discover the Palace, where it all began
Take the power of Artifacts for yourself
Beat the game without dying on at least normal difficulty
Beat the game in under 1 hour
Beat the game in under 40 minutes
Find your first artifact
Have five artifacts at the same time
Have ten artifacts at the same time
Have the max amount of artifacts at the same time
Rescue the Summoner
Have six gold at the same time
Reach max health
Unlock all doors
Have an enemy be infected, burning, slowed, and paralyzed at the same time
Deal a large amount of damage in one hit
Find a chestplate
Find boots
Find the Decapitator
Return to the desert
Find almost all artifacts
Earn all achievements