Here is the full list of all 67 Crystal Maidens achievements.
Upgrade a building up to level 5
Romance 5 maidens to level 3
Complete level 60 of Campaign Mode
Kill 1000 enemies in battle
Win 50 battles with all 3 stars
Complete 10 quests
Play 100 battles with Support class
Play 100 battles with Marksman class
Get a hero up to level 30
Own 15 maidens
Earn 120 stars in Campaign 1
Play 50 battles with Mage class
Play 50 battles with Marksman class
Play 100 battles with Warrior class
Play 50 battles with Support class
Romance 2 maidens to level 3
Kill 250 enemies in battle
Win 20 battles with all 3 stars
Own 10 maidens
Complete level 30 of Campaign Mode
Earn 60 stars in Campaign 1
Upgrade a building up to level 2
Play 50 battles with Warrior class
Kill 100 enemies in battle
Earn 5000 coins in Campaign Mode
Upgrade a skill to the level 5
Get a hero up to level 10
Win 5 battles with all 3 stars
Own 5 maidens
Complete level 1 of Campaign Mode
Get a hero up to level 60
Find a legendary item in the Campaign Mode
Earn 250.000 coins in Campaign Mode
Earn 1 million coins in Campaign Mode
Complete 50 quests
Complete 200 quests
Upgrade a building up to level 10
Play 500 battles with Support class
Play 100 battles with Engineer class
Play 500 battles with Engineer class
Play 500 battles with Marksman class
Play 100 battles with Mage class
Play 500 battles with Mage class
Romance 15 maidens to level 3
Upgrade a skill to the level 20
Play 7 days in a row
Play 15 days in a row
Upgrade 1 common item to the level 5
Upgrade 10 common items to the level 5
Upgrade 30 common items to the level 5
Upgrade 1 rare item to the level 5
Upgrade 10 rare items to the level 5
Upgrade 30 rare items to the level 5
Upgrade 1 epic item to the level 5
Upgrade 10 epic items to the level 5
Upgrade 30 epic items to the level 5
Lose 50 battles
Lose 100 battles
Lose 500 battles
Earn 180 stars in Campaign 1
Find 5 legendary items in the Campaign Mode
Find 10 legendary items in the Campaign Mode
Upgrade 1 legendary item to the level 5
Upgrade 10 legendary items to the level 5"
Upgrade 30 legendary items to the level 5
Play 50 battles with Engineer class