To open the door one must enter the right 4 digit numerical code on a Steelstone number pad embedded into the door. The keys on the number pad are in Paragon Number System. Above the key pad there are four blank glyph stones. Pressing any key will cause a corresponding number glyph to appear on the left-most available glyph stone. The glyph stones remain lit until four numbers are entered. At that point the code is tested and the door either unlocks, or all the glyph stones are blanked.
Entering incorrect code appears to summon two Modron Protectrons who arrive from behind to cut-off the escape route for the intruders.