This game is an excellent tower defense game. The graphics are great and the skill tree is a nice addition. Keeps the game interesting.
My only criticism is the Champion Ninja on level 14. Despite tower defense games being based on strategy, this Champion requires luck. Even with your mana maxed and meteor damage maxed, you cannot kill the ninja before he reaches your gems unless he is (by chance) frozen. It's a very tedious process.
 "Cursed Treasure: Don't Touch My Gems!"){kind=icon}