Immortal Horrors. C'Horthids creep in the darkened chambers of pharoahs, untouched by time or the sun for centuries, and lie in wait for tomb robbers that ignore the warnings painted in heiroplyphics on the walls.
Each C'Horthid is clad in armored plates of black chitine with writhing form of over three meters in length, with a multitude of wretched scythe-like legs running along a segmented thorax that attached to an upright abdomen armed with a pair of toothed scythes for forelimbs. Most horrifying is that rather than an insectoid head it has a large grey humanoid head with cruel red eyes, a mouth full of razors and pincers. They make inhuman coughing noises, like the wheezing croak of a thousand locusts, as they choke on death itself. For it is the breath of the C'Horthid that is the true danger: the black gas it emits from its maw paralyzes its prey. It is then that the C'Horthid's horrifying intent is revealed as it will attempt to devour the soul of an incapacitated humanoids.
The only way to release the souls so they can join the afterlife, once devoured by a C'Horthid, is to destroy the beast.
Mindless Servants of the Scarab. The long term purpose of these creatures is unknown and alien as the mind of their god Khepis but it is believed that they will be rewarded by the swarm lord when he returns to pick the desert clean of all life. Until then, they remain trapped forever in their bodies, which act as a prison for the souls as their prey.
It is believed that some priests of Khepis, as well as other evil beings capable of controlling these insane horrors, are able to use these creatures as personal protectors and have a way to extract the souls to be used as a part of dark rituals involved with the scarab god. Only the most wicked of souls would create or use these monstrosities.
Terrible Weapons. And the have been used for more than guarding dungeons: some priests managed to cultivate and grow C'Horthids of monstrous size for use in warfare. These C'Horthid "invaders" were used as siege weapons, unleashed upon the enemies of the Scarab cult, and a few of them could destroy and consume thousands of souls. These legendary horrors and the rituals to create them have thankfully been lost to the sands of time but there are stories from raving madmen of caverns beneath ruined cities holding these horrors in wait for some darker purpose.