Sorry, but your approach is all wrong. Do not try this. You should be able to go all the way to level 10 with out dropping any bombs or freezing. Bur your learning how not to do it. You should up grade your ice tower too. What it does is slow down the monsters a bit and allows the spell towers more time to kill them. It also seems to make them easier to kill. Don't remove your towers until the last round and only the spell towers closest to the end. Changing a spell tower for a cross bow tower will help focus the attack on the monsters closest to the endpoint. The only cheat going on here is you cheating yourself of points.