The other comments really say what is needed here. Right now they feel like cardboard cutout villains to fill the 'burn the witch'. There is good drama potential with how they deal with heretic priests and the like. Go to Comment
This is quite a good item. Moons comments about the effects on the character is a good one - being in literal Hell should leave a mark.
I would at least have the user now have infernal _attention_. It is not often that a soul gets to leave that place. I'm reminded of an old Dragon magazine comic that showed a character who managed to escape hell one time being waited for by a 'welcoming' committee after his final passing..
Sessiliths (name based on the word sessile) are gargoyle-type creatures which are stationary, attached to the stone of whichever foundation they are bound to. Though they can move their extremities and limbs they are unable to move away from their particular perch. In lieu of swooping down and attacking like their mobile cousins the gargoyles proper, sessiliths are equipped with their own brand of mischief. The creatures are all able to verbalize and thus usually hurl vile insults and curses upon passersby. The cumulative effects of dozens of sessiliths cursing, screaming, and speaking in tongues, can have an effect of temporary confusion (or even discord) in those forced to listen to the shrieking stone gremlins.
Additionally, most possess the ability to "spout" or spit forth various undesirable projections, such as tar, boiling water, or even acid. While they can usually be avoided easily enough or even destroyed (their "bodies" feature the same defenses as gargoyles), sessiliths are usually placed in such a way as to hinder all trespassers and interlopers, narrow corridors, claustrophobic tunnels and other related "gauntlets", where they cannot be easily avoided. Like gargoyles, sessiliths come in all sorts of grotesque shapes and sizes, though they tend to resemble tiny horned devils, demonic amphibians, or simply distorted faces and heads, more often than not.