From Portals of Phereon Wiki
A special trait that can't be passed on.
Mounts override the movement of smaller characters on certain biomes on the Overworld. For example, a small sized character with lava movement, who would normally take 6 minutes to cross a plains tile, can ride a normal sized LandMount with normal movement to cross the same plains tile in 5 minutes. An equally normal sized character with lava movement does not benefit.
Also see Lava Mount, Water Mount, Air Mount.