Here is the full list of all 20 King Lucas achievements.
Complete the search of 3 princesses.
Walk 100 rooms.
Walk 250 rooms.
Walk 750 rooms.
Finish with 100 slimes.
Finish with 150 enemies using magic stick.
Finish with 200 enemies using fire sword.
Use the compass in one search.
Reach the rooftop terrace of the castle.
Find the frog Princess.
Complete the seacrh of the dog William.
Finish with 50 spiders.
Unlock all rooms in one castle.
Use life potion 10 times.
Kill 200 enemies using ice sword.
Use 50 keys to open doors.
Use invencibility potion 20 times.
Participate in one search in multiplayer mode.
Complete one search before anyone in multiplayer mode.
Organize 20 searchs in multiplayer mode.