As the title might suggest, this is an alternate outfit for Gullin, made by Drak.
Seeing as he's based on the nordic beast Gullinbursti, we wanted there to be a nordic outfit for him as well. It'll be something for him to wear during what we jokingly call 'the winter arc'.
In nordic mythology, Gullinbursti (meaning golden bristles) is a huge boar with golden fur (as the name would imply) that can run and swim faster than any horse, with a shining bristling mane that lights up the dark. It was made by two dwarven smiths during a bet with the trickster god Loki. Through the bet, Gullinbursti ends up in the hands of Frey, a fertility god. He's depicted as Frey's beloved mount.
That is the basics, and how much we incorporate from the original story, we cannot say! Certain elements will be there, and some might not. It'll be for you to find out.