Are you want win this game. You should use skill's to Energy Mage. Because Energy mage is so powerful for other mages. And you should buy Archer skill.
Its have fixed this topic. http://www.kongregate.com/forums/7-technical-support/topics/357408-desktop-tower-defense-1-5-broken-game And you need install this script userscripts.org/scripts/show/125484 - Thanks for helping BTrenary.
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 "The Peacekeeper"){kind=icon}
 "Don't Escape"){kind=icon}