The Wayback Machine - https://web.archive.org/web/20190403021329/https://www.visualeffectssociety.com/award-categories/outstanding-visual-effects-broadcast-series
This award is to honor the achievement of the visual effects within a single episode of a series where the visual effects are a visible, essential, and integral part of the story and play a principal and active role in the show. A rule of thumb for defining whether a series would be considered effects-driven would be to ask if the story could be told without the active participation of the VFX (including Special Effects)