Craglings are large, brutish-looking rock being that live in the Land of Madness and are led by King Crag-Nor. They draw their life energy from the mud they consume.
Master Wu and Lord Garmadon traversed through the Mountain of Madness together, making their way toward the summit. However, Lord Garmadon realized that the moon had already risen, commenting that the Craglings would never miss out on a midnight snack. Master Wu and Lord Garmadon briefly chatted before dozens of boulders formed together, which created a group of Craglings.
The group of rocky monsters cornered the two, causing Lord Garmadon to spring into action. Wu managed to take out some with his shéng biāo in single blows. The Craglings gradually chased them up the hill, one catching Master Wu and pinning him down. When it opened its mouth to consume him, Lord Garmadon rushed in and destroyed it with a single blow. The two brothers became surrounded, the both of them being reminded of their past battles as a team. Seeing that their weapons would not do the trick, they both performed Destruction and CreationSpinjitzu in order to defeat them.
At some point after The Merge, the Craglings were attacked by a pair of Earth Dragons, which ate from a mud pool that was a Cragling burial ground. This caused the dragons to become larger and more ferocious, and cause the Craglings to start falling apart. Eventually, Kai and Nya would discover the conflict and get involved in helping the Craglings.
Sometime after Lloyd began training a pairof students and their dragon, the group discovered the derelict Destiny's Bounty and followed Kai's notes stored onboard to the Land of Madness where they initially mistook the Craglings as attacking a pair of innocent dragons. After being reunited with Nya and having the confusion cleared up, Lloyd and his group agreed to join Nya in defending the Cragling village from the dragons.
After a rough battle with the Earth Dragons, Riyu managed to defeat them by overcharging the mud from the burial grounds while the pair fed. This caused the Earth Dragons to release all the energy that they had consumed from the mud, releasing it back into the burial grounds and restoring the crumbling Craglings. With the day won, the Craglings hailed Riyu and the ninja as heroes.
After the Matriarch of the Mountain Dragons was attacked by Nokt and Rox and crashed in the Land of Madness, the Ninja take her to the Craglings to help heal her with their mud. However, the matriarch ultimately dies of her injuries, but not before telling Lloyd that the Source Dragons were in danger, and giving the Ninja a map to the City of Temples and leaving her daughter Eridany to them to be taken back to her tribe.
Later, a Cragling elemental master, Arccrack, would participate in the Tournament of the Sources. Arccrack unfortunately would be eliminated in his first match against Lloyd and later helped to fight against the Wolf Clan when Nokt and Rox attempted to overthrow the games.