Needs a x1000 on the upgrade tab, for the super late game. I find myself spamming the x100, after I let the interest run for a little while. And by spamming I mean like 2-300 clicks per upgrade, which adds up to quite some mouse clicks. If you use the max button it spends too much of your resources and you cant balance out the upgrades (ie. element dmg/res).
 "The Perfect Tower"){kind=icon}
 "Desktop TD Pro"){kind=icon}