Here is the full list of all 21 Echoes of the Fey: The Last Sacrament achievements.
Finish the first game of RiftRealms.
Finish Day One
Finish Day Two
Finish Day Three
Finish Day Four
Finish Day Five
Romance Arkady and uncover the secret of his past
Romance Katerina Lapidus and discover why you spent years apart
Romance Nikolai Melinkov despite the start of your relationship
Romance Heremon ir-Caldy and take your relationship to a new level
Convince Heremon to go back to his new relationship
Use the Sacrament to save the life of your partner in crime
Give the Sacrament to the person who hired you, no matter the result
Use the Sacrament on yourself
Unlock every Codex entry
Find Katerina's attacker and hear his side of the story
Throw fate to the wind and cast yourself into a dark future
Use an item that changes your costume
Assist Katerina in her quest to get her aqueduct approved
Purchase an item or upgrade in RiftRealms
Defeat a dungeon master in RiftRealms in the present day