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