Actually, I rather like this idea. As a sort-of cross between Nuhoch Wallows and the Jackal's Sand Warp, it could operate as specific point-to-point transport, as well as opening up access to completely new areas (teleporting to a different "underground" map rather than a section of the current one.)
I would propose it be an Advanced Ability (like the Skimmer's Dive) or Advanced Mastery (like the Griffon's Aerial Prowess) rather than a new mount, but either way works.