Cosmic horror murals?

Heya! I'm doing a cosmic horror oneshot, taking place in a geometry-defying dungeon made of hands and arms (the severed arms of a creature called mother hand). Anyway, I'm trying to give some clues to her origins (sort of) through murals and a shadow puppet show, while keeping the ambiguity cosmic horror demands. 

(Basically, a while ago, a cult tried to summon mother hand, but her impossible geometries couldn't emerge from the portal, so it was a portal walking around on really long arms and dragging people into it. The portal was closed, but her severed arms burrowed into the ground, made this complex, and sort of infected the people around her, recruiting them into a new cult. Mother hand herself was formed when someone's hand fell into the dream/far realm and was imprinted on by the formless form that would become mother hand. Her new summoning plan is using a willing mortal sacrifice's connection to the dream realm to give her a small bridge (her arms will come out of the sacrifice's ears while they babble incoherently))

Anything helps