The Ward of the Three Witnesses

You find a circular basalt door set into the dungeon wall, its surface divided by three concentric stone rings. Blue-white glyphs pulse beneath the dust, shedding cold light across a frost-filled basin and a cracked owl relief. A bronze plate beside the door bears flowing Primordial script. Whenever anyone touches a ring, the temple answers with a different sign: the basin steams, the owl's eye opens, or the moon-shaped lens dims. Deep behind the door, something gives a slow, patient knock.