Quakedancer

At first sight a quakedancer, also called a quakebeast, quakemaker or thunderer, looks like a long-necked brontosaurus, except that it walks on six legs. It is no true dinosaur. The middle legs end in thick claws that splay outward, pointing both ahead and behind, and their knees are oversized. The front and rear feet are wider at the base than a sauropod of the same bulk would need.

It may chew leaves, but the quakedancer eats meat, and its grazing is a disguise meant to reassure genuine plant-eaters. It lacks the usual predator's toolkit of big fangs and claws, camouflage or speed. Instead, whenever hunger strikes, as it frequently does, it browses placidly until plenty of unwary animals gather around it for the apparent safety it offers.

Then it digs its middle toes into the earth and balances its bulk on them like a pivot. It begins to seesaw from front legs to back, slowly and then faster, heaving with neck and tail and slamming down with each swing. Building up takes 3-6 rounds, after which the pounding sends out shock waves that stun nearby creatures smaller than itself. It stomps once per round, and every round it keeps this up, those in range save vs. paralysis or are stunned for 2d4 rounds. Stunning stacks up to 20 rounds. The creature's growth table sets which sizes are affected and how far the waves reach.

When enough prey lies stunned, about 2d6 victims of the biggest size it can stun, or a greater number of smaller ones, it stops and gulps them down one per round, needing no attack roll. It ignores anything still moving unless that creature attacks, in which case it stomps and bites. A swallowed victim either suffocates under the normal breath-holding rules (a monster uses twice its Hit Dice as its Constitution) or, from the third round after being swallowed, takes 3d8 damage per round from stomach acid.

It hunts only on flat, solid ground far from rival predators, so that no scavenger can dart in from outside the quake zone and steal its catch, and no cracks or rockslides swallow the prey. Older, bigger beasts grow careless about this, since terrain that daunts a 6-foot human matters little to a 50-foot quakedancer.

It keeps no lair, because local wildlife soon learns to avoid any place it shakes again and again. It roams in search of grounds where animals do not fear it yet. A tracker can follow one easily, even years later, by the slowly healing scars it leaves in the land.

Once a year a female lays 2d10 eggs, each 4 feet long, in a shallow pit in the middle of freshly ravaged ground, which other creatures tend to avoid for a while. She leaves them, just as the male left her weeks earlier. Most eggs hatch, but few young last a year, falling to predators or to their own siblings. Too light to make quakes, hatchlings flee into cover and live on plants, insects and small prey. Survivors of that first year can stun Tiny creatures close by, and from then on their success is nearly certain. They grow astonishingly fast, reaching 50 feet and breeding age in their fifth year.

Despite the devastation, a quakedancer barely changes its surroundings over time. Animals return soon after it leaves, and many stunned animals wake and get away, so it never overhunts. It may shift a stream's course, or now and then set off a worse disaster such as an avalanche, a landslide, a real earthquake or a flood from a broken dam. Farmers and city folk, tied to fixed land, find it intolerable and have exterminated it from most regions.

Anyone who knows where to search can find its eggs, but worth little given what hatches a few years later. Swindlers sell them as dragon eggs, and some people mail them anonymously to enemies; towns burned by such jokes often outlaw bringing in, selling or owning them.

Legend says quakedancers never die of age. Predators, hunters, sickness, disaster or a bigger quakedancer can kill one, but otherwise it simply keeps growing. Where this belief runs strong, every earthquake is blamed on a colossal quakedancer passing by, or on the shock waves of a half-legendary first and greatest of their kind said to roam distant lands.