Makhfiir

"The hill looked like a blessing, after the morning sun had beat upon Farid for hours. He decided to pause early, and wait out the hottest part of the day in the shade provided by the craggy rock. As he drew close, he caught a strange scent on the air - almost as if there was some fetid pool of water nearby. He peered into the crevasse that split the rockface before him, wondering if there might be some liquid deep with it. There was a sudden movement in the dark, and then he was fighting for his life as a tentacle whipped around his neck and pulled him against the rocks, smashing his forehead and leaving him dazed. The pressure increased and Farid felt his neck bend too far, and then heard a cracking sound amidst blinding pain. Farid knew nothing more after that." - An encounter with the Makhfiir, as told by storytellers in Al-Tana

In the arcane desert of the Al-Kubra, there exists a terrifying monster called the Makhfiir, or the Lurker in Shadows. It is an ambush predator, with a gigantic outer shell that looks like a large boulder or small hill. The shell is bleached pale by the relentess sun of the desert, and it has a rough, irregular shape with numerous overhangs and deep crevices. In the harsh light of the desert day, it is often the only source of shade for miles around, and the hope of a respite from the glare draws its prey close.
From within the shell, the creature scans the landscape, watching for whatever may approach. It is patient, waiting until something is too close to flee before striking. Once a meal is as close as the Makhfiir thinks it will come, it lashes out with one or more of its eight ropy tentacles. They can reach out dozens of feet from the shell, seeking to seize the careless animal and draw it through the shadowy crevices into the shell within. The tentacles are ferociously strong, and can pull hard enough to crush the bones of a creature too large to fit into the shell whole, leaving body parts lying on the sand until they are collected by the monster's other tentacles. Once inside, the creature is ripped apart by the Makhfiir's tentacles and beak, and crushed into chunks small enough to be swallowed. Once the prey is consumed, the Makhfiir carefully licks up any blood left inside or outside the shell, wasting no liquids that it can possibly extract. It's tongue is long and pointed, and it can use it much like another tentacle, although it cannot reach as far.
The Makhfiir can survive for months on a single meal, and can enter a state of dormancy for years if need be. Sometimes, newcomers to a region will pass near the shell several times while it sleeps, never suspecting that the 'hill' is actually the shell of a beast. It rarely moves from its resting place, but it is capable of it. It will most often choose to relocate during the rare rainstorms that flood the desert.