Here is the full list of all 20 Duke of Defense achievements.
Complete the tutorial!
Teleport for the first time!
Collect 50 coins in a single streak!
Build 250 towers!
Defeat 500 enemies!
Defeat 2500 enemies!
Collect 5000 coins!
Collect 25 gems!
Complete 100 waves!
Unlock 5 heads!
Equip a head that isn't the default!
Survive your first encounter with the Fire Wizard!
Become an apparent successor!
Unlock 15 heads!
Unlock 30 heads!
100% complete the game!