Bulette

A bulette is an armored, plated predator that burrows through the earth and emerges to surprise and consume its prey. Commonly referred to as a landshark, the bulette is a fearsome hunter. Its thick carapace makes it very difficult to damage. A larger, elementally infused bulette called a magma bulette exists in volcanos.

Abilities
The following is taken from the Monster Manual, 5th Edition, p. 34, but is consistent with what is demonstrated onstream.
 * Standing Leap: Bulettes can make a 30-foot long jump or a 15-foot high jump even without a running start.
 * Deadly Leap: If the bulette jumps at least 15 feet to a space with other creatures, those creatures must make a Strength or Dexterity saving throw. On a failure, they are knocked prone in the bulette's space and take full bludgeoning and slashing damage. On a success, they take half damage and are pushed to a nearby space if possible; if there is no nearby space to be pushed, they fall prone in the bulette's space.

Magma bulette
Magma bulettes can also leap at enemies, but have additional abilities. Magma bulettes do not have eyes, and thus do not have darkvision, so they are reliant on tremorsense and unable to detect creatures flying nearby.

The full-grown magma bulette does fire damage to creatures standing next to her, even after dying. She also deals fire damage when biting, and on an attack roll of 18 to 20, she swallows the target, which causes them to be blinded and restrained. Swallowed creatures take heavy fire damage on their turn, but if the bulette takes more than 40 damage, it must make a Constitution saving throw or spit up the swallowed creature, which falls prone.

History
A bulette stalked the members of Vox Machina as they ventured into the Underdark. It eventually attempted to seize its prey when it emerged in the midst of a duergar warcamp in the thick of battle. Upon returning to Emon, Vex'ahlia commissioned a blacksmith named Karen to create custom armor for Trinket out of the pieces of carapace harvested from the bulette.

Vox Machina encountered a variation of the bulette called a "magma bulette" in the underwater volcano Scaldseat. These bulettes were infused with fire and magma, to the point where the heat radiating from their bodies was enough to cause damage. The adult magma bulette was much larger than a standard bulette, able to swallow Grog Strongjaw whole.