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 or magma landshark exists in volcanoes and in the Elemental Plane of Fire.

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 (or magma landsharks) can also leap at enemies, but they have additional abilities.

In, 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.

Several of these features are shared by the magma landshark in Tal'Dorei Campaign Setting Reborn, with small changes. Instead of swallowing a creature based on the attack roll, the bitten creature must succeed at a Dexterity saving throw, and the landshark regurgitates the creature only if it takes 30 damage from a creature inside it. However, the magma landshark does have darkvision, and its tremorsense range is doubled to 120 ft. In addition, the magma landshark can, as an action, melt the solid ground around it into lava, dealing fire damage to creatures that enter that area. A young magma landshark cannot swallow creatures it bites and cannot create a lava pool, but unlike the baby magma bulettes in, young magma landsharks automatically deal fire damage to nearby creatures.

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.

Thordak's invasion attracted magma landsharks from the depths beneath the Cliffkeep Mountains to the surface for decades to come, and they notably nested under Serpent's Head. A whole herd of magma bulettes from the Cliffkeeps unaccountably attacked Westruun's Market Ward not long before 836 PD, to the benefit of the League of Miracles, who were paid to do the cleanup.