The final boss of this game is the avatar of Grima. Who happened to be a dragon, and is connected to the Earth Dragons. Most of the games with Earth Dragons featured non-mounted enemy dragons except for the Jugdral games. And it was established for those game that the non-mounted dragons don't really hang around there that much and Loptyr went there during the Divine Dragon VS Earth Dragon thing.
Really, this game could have had some Draco Zombies like Gaiden and Sacred Stones at least if Grima!Robin couldn't get any degenerated dragons or manaketes to help him.