Here is the full list of all 24 Secrets of Magic 2: Witches and Wizards achievements.
Upgrade twice the Whirlwind power-up
Upgrade twice the Stake power-up
Upgrade twice the Lightning power-up
Get 300 stars
Finish all the levels in Challenge mode
Collect at least 78 crystals of any kind
Upgrade twice the Wand power-up
Destroy at least 28 spiders
Destroy at least 50 big rocks
Get 200 stars
Destroy at least 380 stones
Play 50 levels
Upgrade twice the Hammer 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
Upgrade any power-up for the first time
Play 20 levels in a row
Explode at least 30 bombs - bonus power-up
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