This opal glows with multihued light, and ornate arcane symbols have been etched into its surface.

A greater glyph seal allows you to convert any arcane or divine spell of up to 5th level into a symbol similar to a greater glyph of warding.
To do so, you must cast the spell while holding the seal; doing this is called keying the seal. You can safely transport a keyed glyph seal until you activate it by pressing the seal to the desired surface.
The seal can adhere to any nonmagical, nonliving object. An activated greater glyph seal functions as the spell glyph function of a greater glyph of warding and can be detected and disabled as a magic trap (DC 33).
A greater glyph seal is unaffected by the spell within it. Once activated, the now-empty greater glyph seal can be retrieved (though it requires a successful DC 33 Search check to find) and used. You can always remove any greater glyph seal you keyed and activated to redeploy it elsewhere.

Prerequisites: Craft Wondrous Item, greater glyph of warding.
Cost to Create: 2,000 gp, 160 XP, 4 days.