Comparable to gems, a number of "elder uniques" were added in War for the Atlas that can only fall from The Elder himself. Game Designer Hrishi took some time to discuss the Cyclopean Coil, Blasphemer's Grasp, Nebuloch, Hopeshredder, Shimmeron, Impresence along with Watcher's Eye. Each has its own distinct niche in POE Currency  , both in terms of its unique look, but also with regard to what it increases the overall player experience through characteristic focus, ailment focus and much more.

[T]he unique items needed to be made in such a way that made them generally useful for a vast array of builds, and to make a reason to keep fighting with the Elder many times, or the things would feel as though they had no worth.

The general design of a good deal of older uniques is that they're intended for a big variety of builds. As a result of this, the focus on those designs are attributes, diseases, charges, curses and auras.

Throughout 2017, Grinding Gear was a busy company with expanding Cheap POE orbs . The article further goes into details about Support Stone and how layout iterates in concept to completed job. You can check it all out here.