Elemental Artifacts are items applied to a character's action skill. They can be obtained through missions and also dropped by enemies and bosses from time to time. The earliest mission you can get one is by completing Shock Crystal Harvest, which is available via the Fyrestone Bounty Board when you are level 14 (may need to have progressed a certain amount through the main storyline as well). Once you equip an Elemental Artifact to your character, the trophy will unlock.
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