Here is the full list of all 20 Magic Masks achievements.
Hop on to the Island
Mastered the basics
Complete Lido's first quest
Complete Lido's second quest
Complete Lido's third quest
Complete Rosy's first quest
Complete Rosy's second quest
Complete Rosy's third quest
Acquire Lido's first mask
Acquire Lido's second mask
Acquire Lido's third mask
Acquire Rosy's first mask
Acquire Rosy's second mask
Acquire Rosy's third mask
Complete the game