Here is the full list of all 24 Secrets of Magic 2: Witches and Wizards achievements.
Collect at least 78 crystals of any kind
Finish all the levels in Challenge mode
Get 300 stars
Destroy at least 28 spiders
Upgrade twice the Lightning power-up
Get 200 stars
Destroy at least 50 big rocks
Destroy at least 380 stones
Upgrade twice the Hammer power-up
Upgrade twice the Whirlwind power-up
Play 50 levels
Upgrade twice the Stake power-up
Upgrade twice the Wand power-up
Destroy at least 280 spider webs
Destroy at least 650 wooden gates
Destroy at least 120 imps
Upgrade twice the Torch power-up
Explode at least 30 bombs - bonus power-up
Play 20 levels in a row
Upgrade any power-up for the first time
Finish the first 10 levels with 3 stars in each level
Make a combo of 25x or higher
Make a combo of 20x
Make a combo of 15x