The 100 Strategy (Help)

[Xenmas]

So. I've recently been drawn back into DTD. I have no real hopes of making the high score boards (Which ticked me off with "Survivor" because I did have a perfect game just 4 points shy). So now, I am attacking "The 100".

I've got the juggling thing down, I think. It's a little tough at first, making a maze that is more designed to juggle than for a kill 'em all quick, but I'm managing. What I can't manage is the fliers. Usually around the 60s-70s the fliers leak, almost all of them in a single wave. I usually reset around that point because I know I won't be able to defend against the next wave of fliers. Everything else I can control with Juggling, how do people set up the center of their mazes?