The Rumblehorn has relatively large wings, a wide torso, and a tail with a club-like hammer on the tip. Its most notable feature is the heavily armed front half of its body with firm armor plates on the neck and a large lower jaw, a battle axe-shaped muzzle, which is always digging in the dirt, looking for scents, and two, very sharp, elongated horns resembling those of ceratopsian dinosaurs, but lacking a beak. The Rumblehorn has a very acute sense of smell, and is determined to track down and find anything once it has picked up the scent. In total, they look like a mix of truffle pig, a rhinoceros, a battle axe, and a scarab beetle.
It can also shoot long-ranged fire "missiles" from its mouth which initially starts out as a white-hot fireball that quickly solidifies and turns to a warmer color before it ends up in a sooty stony material when it hits its target.