Tower idea: "Emergency Fortifications"
So, we've all been there. Someone gets caught out of position at 20 min and by 21 min you've lost all three of your middle towers. This is not okay.
My solution? Emergency Fortifications. "The previous tower was recently destroyed. This tower takes only 50% damage for 30 seconds."
Nothing too crazy, but enough to at least slow down a snowball before it gets too big.
Nobody expects the banana.