Here is the full list of all 25 Buff Knight Advanced achievements.
Clear Stage 1
Kill 1000 Monsters
Solve Fairy's Quiz 5 times
Kill 500 Monsters
Kill 100 Monsters
Use HP Potion 10 Times with 10% of Full HP
Kill 1 Dragon
Kill 5 Dragons
Kill 10 Dragons
Collect 10 Artifact
Collect 20 Artifact
Collect 20 Artifact and Upgrade Complete
Enchant 10 times
Enchant 50 times
Enchant 100 times
Complete Last Stage
Complete Last Stage + ?
Air Combo 20 times
Air Combo 50 times
Air Combo 70 times
Solve Fairy's Quiz 10 times
Solve Fairy's Quiz 15 times
Died 100 times
Get the money 1,000,000,000
Get the money 10,000,000,000