The Groundshaker is an Emblem Heartless that is found in Kingdom Hearts II. It is one of the bosses at Pride Lands. It is a gigantic version of the Living Bone and Shaman combo, fused from the many ghosts of Scar that appeared throughout the Pride Lands.
The Groundshaker is a titanic Heartless reminiscent of a Shaman and Living Bone. The Living Bone analogue has a body almost completely covered in grass, moss, and other plant life, to the point that several trees have grown on it. Each of its legs are yellow with brown armor on them, with white designs decorating the armor. Its feet are steel blue, and each sports three skeletal toes. Its skull is grey with angular, white designs on it and several bent, red horns all around it. Depending on the way its head is turned, it has two different faces; one looks slightly downward and has large, curved tusks lined by spikes, and the other looks slightly upward and has curved horns lined by spikes. Both heads share the same yellow, spiral eyes.
The Shaman analogue is also covered in foliage, albeit to a lesser extent than its companion, and is not always visible. While still massive, it is smaller than the “Living Bone” and rides on its back. It has grey skin, red claws, and four pairs of arms; the lower pair being smaller than the upper one. Unlike its steed, the "Shaman" has three faces, as it wears a special mask that periodically twists upside down over a main face on its neck. One face has gold horns, a curled, yellow "mustache", and a jagged mouth that smiles slightly. The other has a dull green "mustache" and a mouth that frowns slightly. The last is a plain black, sporting two yellow eyes. Both faces of the mask are white, have eyes with spiral pupils, and a green crest decorating its sides. The Groundshaker has four Heartless emblems on its body in total; one on each of the "Living Bone's" foreheads, and one on each of the "Shaman's", except for the neck.
In Kingdom Hearts II Final Mix, the "Living Bone" has yellow spikes on its skull. Its downward-pointing face is now red, while the other half of the skull is still black. Its feet and neck are red and its legs are yellow. The "Shaman" has a predominantly red body and the crest on its mask is orange instead of green.
The Groundshaker's name references its immense size, and the fact that it causes tremors each time it steps.
 Kingdom Hearts II
After Simba finally confronted his doubts and weaknesses about being the ruler of Pride Land, the many Scar's Ghosts which had been haunting him flew to the Savannah and coalesced into a giant Heartless which resembled the Living Bone-Shaman symbiote. After a battle which raged all across the Savannah, Sora and Simba managed to defeat the Heartless and bring peace back to the Pride Land.
The main thing to remember is that the only available targets are its eyes and the shaman-like Heartless on its back. At the start of the battle a series of reaction commands become available helping Sora jump from the ground stomps of the Groundshaker's feet. The computer controls your movements, so you don't get confused. With the last reaction command you will eventually jump up and parry one of its stomps by pressing rapidly, when you do this it will fall and become stunned. Now is your chance to unload the most damage you can to its main head's eyes. Magic, melee, Simba's limit, anything that deals damage. The Groundshaker can't be defeated by attacking the eye. The finishing blow must happen on the shaman-like heartless.
When the Groundshaker recovers, it will jump high onto the air. Make sure it doesn't squash you on the way down. Now, the shaman emerges, so you can jump on its back using the reaction command "jump" twice. There is a shaman monkey-like Heartless here that is the hardest part of the fight. At high health you can attack any of the two heads to take off HP while it casts mild magic that you don't have to worry about if your within melee range. A tip for taking this down, while attacking in the air, press to perform Finishing Blast, this will knock its two heads off on the ground for a short period. At this point the two Heartless unite, allowing Groundshaker to summon fire that will track you if you are too far away. Eventually, Groundshaker warps to the other side of the gorge surrounding the battlefield. It will leap over, damaging you if you are nearby, then it will run away. If it runs away then repeat the process of reaction commands from the beginning to get back on its back.
When it is upright again on the Groundshaker's back the witch-doctor can become invisible. When the witch doctor's double-mask rotates, Groundshaker's head would also rotate. One side uses volcanic fire attacks, while the other side uses eerie electric magic. During this time it is advisable to run clockwise around the boss's back until it is visible again, then try and stun it with the air combo just mentioned. The duration of invisibility and the intensity of magic attacks becomes more frequent as its HP drops lower. As with all boss battles heal well, for this boss never lets your HP go down to less than about half of the first circle around Sora's portrait, it can kill you with one shot if your health is any lower than that in Proud Mode.
When you fall off the back jump up the leg or the head to get back on. Don't stay on the ground when the Shaman is on its back. You will get bombarded by magic attacks and this makes it almost impossible for Sora to survive (good time to use Reflect), let alone get back up.