Here is the full list of all 17 Halloween Mysteries achievements.
Complete a level within 7 min
Complete the whole game
Defeat the Daemon boss
Find all the bonus levels
Die within 5 sec
Kill a boss within 1 min
Kill the Nightshade lvl 10
Defeat the Skeleton boss
Level up to lvl 50
Loot everything in the tomb
Defeat the Toad boss
Open 30 big chests
Collect 40 bugs
Defeat the Pumpkin boss
Destroy the Ghost House
Kill 50 enemies
Complete the tutorial