Instance Set
An instance set is a collection or composition of static mesh actors which can be applied as a "scatter pattern" to populate Unitscape shapes with geometry, that can be transformed, grounded, randomized and even conformed to the underlying geometry(such as a landscape actor) on a per-shape basis. Instance sets provide a great way to infuse "artistic vision" into otherwise purely procedural object scattering.
Here are a few examples showing different types of "instance sets" applied to the same shape with different settings:
Generally speaking the wider the instance set(and the more objects in it) the better the visual result since this reduces pattern repetition when tiling and also provides more flexibility when transforming the instance set gizmo on each shape. Ideally an instance set should be wider than the shape it is being assigned to.