Orbs are an unlock that rotate around the tower and instantly kill most enemies they touch.
There are two main types of orbs:
Orb Speed - Lab values, costs, and duration (20 levels)
Extra Orb Mastery - Lab values, costs, and duration (9 levels)
Workshop orbs have a minimum range of 60m. This means that when your tower range is less than 60m, the workshop orbs will extend past your tower range. With workshop enhancement, you can also increase the size of your orbs.
The Extra Orb Card adds additional orbs that act differently from your regular workshop orbs.
The Orbs Perk increases your workshop orbs by up to 2 more.