Sacred glyph

Sacred glyphs were one of the three types of drow runes, the other two being house defense glyphs and way-marker runes.

Description
Drow runes were always limned in black, be it with ink, paste, or inlay. The runes were elegant. The form was always that of female drow lips that formed a circle out of which eight spider legs grew.

Powers
A sacred glyph stored magic and unleashed it when triggered. The magic was triggered when someone who was not a priestess of Lolth passed over the rune. One way for a priestess to turn those runes inert for two to nine minutes was to speak a password while touching them. The kind of magic was the same as that of way-marker runes but included other powers, typically the creation of nine rubbery 20-ft (6-m) tentacles similar to Evard's black tentacles, a shadow flares effect, a forcecage effect, a sink effect, a feeblemind effect, a polymorph other effect that turned the subject into a spider, and an effect that turned the rune into an explosive fire trap. Still other effects were devised by runecasters to mark and protect special locations. A way to determine whether a priestess had lost the favor of Lolth was to see whether a sacred glyph affected her; if it did, then she had lost favor.

Sacred glyphs were used for the purpose of marking and protecting sacred sites to Lolth, which meant valuables like magic items or sources of wealth like a gem node that belonged to the priesthood of Lolth. The only other drow faith that made use of sacred glyphs was the one of Ghaunadaur. However, they used it only rarely and when they used it, they never made use of the forcecage and polymorph other effects but had a favorite in the sink effect.

History
By the 14 century DR, the technology to create sacred glyphs was already old.