A simple one to miss, but fairly easy to get. When you are turning in your parts and balloons back to Mella so that she constructs the beholder, choose the option below to deliver a message from one of the part sellers.
This achievement was probably missed by some in the first week or two because the return to Mella part would autocomplete and you would get the beholder without having to go to Mella.
LEVIATHAN--19.3k Metallic Dragonborn Guardian Fighter Swordmaster Loadouts
Guild--And the Imaginary Friends
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