Small update. This one adds a generic 2% increase to all damage.
You shouldn't actually see this one, but it's better than "NEW TEXT". :)
If you see this upgrade, if you could please file a bug report and just note what level you're on, and if there's any other information that may help.
The game looks for what towers and orbitals and damage types you have and eliminates those that aren't useful for you. If it can't find an upgrade for you, you'll get this generic default one. BUT - there should always be an upgrade for you.
Thanks for the help!