Razorsnakes are fey creatures that make their home in the Razorgrass Fields of The Feywild. Although quicklings have been known to traverse the fields, the razorsnake is one of very few creatures to call the fields home.
In addition to being able to slither quickly between the blades, the razorsnake also possesses a unique magic and build which allow it to bite through and even consume the grass itself (which slices through literally anything it touches). In fact, The Party used this to their advantage while traveling to Sunhallow. They recruited several of these creatures to "eat" a path through the fields in order to save precious time in the fey.
The snakes were amenable to this deal after Johann VonGruppen used Prestidigitation to make the grass taste like chocolate and Grihymm Phrahdrandon commanded the snakes to try out the newly flavored grass.