In the midst of this area of grass-covered hills, on top of a hill somewhat shorter than those surrounding it, lies a group of large, rounded, heavily weathered stones with a number of large glyphs deeply incised upon each of them. These boulders are roughly 3 feet in height, and generally measure about 8 feet long by 4 feet wide, with a variance of about a foot in either direction. There are 8 of them, arranged at the points of the compass. Around the bottoms of each of these stones are a number of blunt projections, appearing somewhat like stunted legs. In the center of the arrangement of boulders is a large, circular stone, the Focus Stone. This central stone is about 12 feet in diameter, and is flat and flush with the ground. It is deeply carved with complex glyphs and long, sweeping lines and curves.
If the players are unfortunate (or unwise) enough to find themselves waking up bound to these stones, the function of the blunt projections is clear. They will be tied, immobile, with heavy woven-grass ropes to the stones, with the projections used as anchors or tie-offs. From the moment the first PC awakens, they have 1d12+10 minutes before the Sea Mother appears! She will be accompanied by 1d4+1 of her inhuman brood. They will arrive via a secret opening in the flat central Focus Stone. If the PCs have not managed to free themselves before this time, they are at least not gagged. However, they will have to be glib indeed to dissuade the Sea Mother from her intended course of action, which is, quite simply, the ritual sacrifice of all the PCs, one at a time.
The ritual begins with 1 round of casting, involving not only the Sea Mother, but all her accompanying brood as well, gathered in a tight circle around her at the center of the Focus Stone. At the end of this round, a brilliant (even if it happens to be daylight) green-white pillar of light will audibly blast upward toward the heavens, out of sight. The minions are now free to guard her, or undertake other actions, but will default to standing around the circumference of the circle while events proceed. If left to her designs, the Sea Mother will then begin using a large ceremonial knife to uncomfortably dispatch the PCs, beginning of course with any hapless henchmen or hirelings. With each sacrifice, the glyphs of the poor unfortunate’s stone glow with bright greenish light. A brilliant green-white shaft of light then springs horizontally from the blood-soaked boulder to join and strengthen the pillar of light at the center. If she completes the ritual, and some PC is somehow yet left alive (perhaps watching from a nearby hilltop, the coward!) the Sea Mother grows 3 feet in height and length, grotesquely sprouts yet another pair of arms, and gains 2 hit dice.
At the DM’s option, one last chance exists for each of the PCs as she, in turn, tries to send their souls to her dark god. If they can make a dexterity-based saving throw, they manage to interpose a woven rope between their flesh and her glittering blade. They thereby free a limb of their choice, and may begin a desperate last-ditch struggle for survival.
If the PCs arrive at the location in more agreeable circumstances, they have the usual chances to discover the secret door. Opening it will require dripping fresh blood (the door is not picky about whose) into the shallow, 6 inch bowl-like depression in the center, then using this liquid to trace 8 small glyphs on the surface of the Focus Stone. Each of these glyphs is near the perimeter, each one ‘aimed’ at one of the surrounding boulders. (Remember, the Focus Stone is bare to the elements, making any blood stains terribly faint) The Focus Stone will then grind open, iris-fashion, revealing a very steep, time-worn and lichen encrusted stone stair. The stair leads to a tunnel, which then snakes its way through the earth to location ‘d.’
The only random encounter possible in the tunnel (unless the Sea Mother knows strangers are on the island, in which case a lone brood minion may be patrolling) is black garbugs. The chance is 1 in 6 for every 30 minute period. Roll a d30 to determine when (and thus where) the encounter occurs.