Here is the full list of all 36 Secrets of Magic: The Book of Spells achievements.
Get 300 stars
Use the Torch power-up on at least 25 spiders
Complete the Venom Antidote Spell
Finish all the levels in Challenge mode
Complete the Spell of Awakening
Get 200 stars
Complete the Spell to Remove a Werewolf’s Curse
Collect 500 spell ingredients
Complete the Spell to Hear Secret Thoughts
Complete the Spell of Invisibility
Upgrade twice the Whirlwind power-up
Complete the Spell of Truth
Finish the first 10 levels with 3 stars in each level
Destroy at least 600 wooden gates
Upgrade twice the Wand power-up
Play 50 levels
Complete the Spell of Healing
Upgrade twice the Stake power-up
Destroy at least 130 stones
Upgrade twice the Lightning power-up
Upgrade twice the Hammer power-up
Complete the Spell to Fly a Broom
Upgrade twice the Torch power-up
Destroy at least 245 spider webs
Complete the Spell of Time
Make a combo of 25x or higher
Destroy at least 100 imps
Complete the Spell for Invoking the Power of Lightning
Upgrade any power-up for the first time
Complete the Spell of Strength
Complete the Spell for Invoking the Power of Wind
Complete the Spell to Imprison an Evil Spirit
Complete the Spell for Invoking the Power of Fire
Make a combo of 20x
Make a combo of 15x
Complete the Spell of Protection