The Deer-Fox herd is a herd of Deer-foxes, and Twig's former herd. Twig's father is their alpha.
The herd appears in Season 2 during the episode "Chapter 9: The Deerfox". In this episode, Twig is reunited with his herd when he runs away from Hilda and back to the wilderness. The herd consists of multiple adults and their young. They are about to leave to their home dimension again, and this time Twig goes with them (last time they were on Earth, he missed the chance because he ran off to rescue Hilda from an eagle), but soon changes his mind.
They appear again in "Chapter 8: The Fairy Isle" when Twig summons them to help him rescue Hilda and Johanna from Fairy Country. With their light-bridges, the herd is able to travel to Fairy Country, where they fight and defeat the Eyes before retreating back to the human world with Johanna and Hilda.