If you have an unpgraded nature tower and "Uproot" you can walk through it AND make another tower on top of it. So then with the second tower, you uproot it and now you have 2 towers in one spot. Spam this 40 times, or until you are unable to select the rooted tower, and keep making them till you get bored, and you will have a pretty op base. Although a few spinies/aura trees help too

The only way to select the towers effectively is to scroll down your camera with the normal mouse wheel scroll, and box(drag) select the bottom of the tower, near the shadow, until you get it.
Here are some shots

-cam 100

-cam 100

Also note, if you place two uprooted towers 1 space away from each other (they are now half overlapping each other), you get a big messy glitch. If your cam is in a certain area (which happens to be most of the base) you get... well this:
-cam 100

-cam 250

I have also attached the replay for anyone who cares to watch it. We start to base just after the first minion is killed. Titan doesn't attack us and die until the very end.