Build 50 mines
Fully upgrade any tower in the store
[Invisible Threat]: Pass level without spells
[Invisible Threat]: Use the spell 200 times
[Invisible Threat]: Kill 1500 enemies
Kill 500 enemies with spells
Sell 50 towers
Make a complete improvement for 50 towers on the levels
Kill 1000 enemies
Build 50 towers
Kill 3 enemies with one spell
Sell 500 towers
[Invisible Threat]: Complete all levels to 3 stars
[Invisible Threat]: Kill 5 enemies with one shot
Build 1000 towers