Here is the full list of all 23 Moonchild achievements.
30 creatures summoned
Gabriel - 100 kills
5 quests completed
2,500 gold coins
Calypso - 100 kills
1 hour played
Kenneth - 100 kills
Susanna - 100 kills
Rupert - 100 kills
Stardust - 100 kills
Dabbabbu - 100 kills
Jardel - 100 kills
Om - 100 kills
Calypso - 1000 kills
Susanna - 200 magic kills
Om - 666 kills
Jardel - 100 magic kills
10,000 gold coins
100,000 gold coins
16 hours played
Calypso - Lv 50
Talk 16 times
All quests completed