Good point. I'll test it out. Do you think two hourglasses are enough?
You're using seven towers to fuel two hourglasses (the Supernovas pay for the dragon), which seems quite inefficient unless you're using unupped Sundial.
EDIT: Nope. Having only two hourglasses kills your win rate; you can't get to your Sundials in time. In one memorable game, I had to let the chain fall so much that even when I got the chain up and running again I was at 2 HP and staring across Neptune's Poseidon.
The most humiliating part of it all was that I had just drawn the last part of the combo, but not enough Supernovas to play it.