In v1.6.7 that's the last wave of the survivor level. The 70 Caspers are meant to be unbeatable. There are however ways to beat them, but the game will end anyway.
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I used the teleport as many times as I could - and had loads of money and just spammed the 'repair' button, but it wasn't enough! Great game, though! One very small bug I found - I was down to 3 health, then wondered what the envelope icon was in the bottom left. Clicked it and it said to repair the castle, but it changed the repair icon to a heart and you can't then click it. So you have to wait to get damaged once more, then you get the repair icon back.