Here is the full list of all 24 The Impregnation of the Elves: Conquest of the Arrogant Fairies by Impregnation achievements.
Defeat all the Elves in Challenge Mode
Achieved Ending 2
Unlock all achievements
Defeated by Idun
Destroy Idun's armour completely
Destroy Frigga's armour completely
Destroy Vivian's armour completely
Destroy Nineve's armour completely
Destroy Dryad's armour completely
See the Goddess' True Form
Achieved Ending 1
Victory over Idun
Victory over Frigga
Defeated by Frigga
Victory over Nimue
Destroy Nimue's armour completely
Defeated by Nimue
Defeated by Vivian
Victory over Vivian
Victory over Nineve
Defeated by Nineve
Victory over Dryad
Defeated by Dryad
Passed a question once