Tesurioth has a long, slender body similar to other Leviathans, covered with a rocky carapace and some spiky protrusions growing on its back. Its front limbs are big and have wing-like fins to swim at high speeds. Its tail is quite long with a spiky fin running through the lower part. Tesurioth head is quite armored and has an elegant frill around the neck. The upper body has a dark navy blue tone, while its fins are striking orange and red and its belly is grayish with cyan marks.
Tesurioth is a great Leviathan found in the waters of volcanic areas and more rarely in marshlands, it prefers to live in abyssal zones. Thanks to its hard shell it can resist high pressures easily. Tesurioth is known for going out of the water to feed on firestones, similar to Gravios, this grants it the ability to use fire to attack and hunt down prey like aquatic monsters or fish.
Tesurioth is known for being agressive towards other predators and hunters, it will use fire to defend itself. It is also known for having a terrible screech similar to Diablos.
Tesurioth can use physical attacks such as charges, tail attacks, bites and hipchecks. It can also use its large fins to create water pressure and hit the hunters, this also helps Tesurioth to propel forward and swim at greater speeds to attack and maneuver. It can also perform jumps and underwater somersaults to attack. On land Tesurioth attack can jumping, charging, rolling, twisting, doing body slams, hitting with its front fins and sliding at high speed.
Using its fire abilities, Tesurioth can spit fire projectiles at hunters, this attack can inflict severe fireblight on land, but not underwater. Enraged, this monster can also expel hot gas that will inflict fireblight on land, underwater it will make water boil around the monster, damaging hunters that are too close to it. Using this fire gas Tesurioth can also create boiling water barriers with some attacks that will inflict damage if hunters cross them. Its most remarkable attack is its super screech, similar to Diablos or Tigrex, that will deal damage if hunters are too close to it.
Its pin attack consists on taking a forward bite, then twist around a hunter and slowly expel hot gas, draining the hunter's health slowly.
- Its frill, back, both front fins and tail can be broken, and after breaking the tail can be severed.