One of the biggest, baddest Lovecraftian beasts of all time graces our page today: the shoggoth. The shoggoth is to a gibbering mouther what Carcharodon megalodon is to a dogfish. It’s a tarry, protoplasmic mess that creates and discards mouths, tentacles, and organs as necessary, all the while making its maddening cry of “Tekeli-li!”
Shoggoths are good penalty encounters—what happens when the PCs fail to stop the Big Bad Guy from pulling the Bad Lever. Or they can be monsters too great and terrible to fight. As an example of this, a weaker shoggoth was introduced to 3.5/Pathfinder courtesy of Wolfgang Baur’s Crucible of Chaos, meandering through a crashed Shory city. PCs were never seriously meant to fight the creature; it was merely meant to keep them on their toes as they explored. Or it can be a harbinger of truly great and dark mysteries from your world’s past or the depths of space. If PCs defeat a shoggoth, they haven’t just struck a blow for good; they’ve struck a blow for this reality vs. another else entirely.
One last note: The shoggoth is one monster where a player’s out-of-game knowledge will only hurt rather then help them. Tell the players who make their Perception checks that they hear a far off cry of “Tekeli-li!” Then sit back and watch the in-the-know players squirm as they realize their GM was wicked enough to throw a shoggoth their way.
An aboleth heirophant faces off against adventurers in his undersea lab in a climactic battle. Pausing before a horrible cyst-like egg, the aboleth boasts of having reawakened and tamed one of his people’s greatest creations. He is wrong on the second count—shoggoths are far older than the aboleth race, and the protoplasmic monster is by no means tame.
Every solstice, adventurers have a dream where they are taken to a barren tundra to fight a gibbering mouther. Every equinox, they have a similar dream…only this time, they are the gibbering mouther devouring helpless prey. When, at the climax of their careers, they find themselves on the frozen demiplane from their dreams, they realize the visions were portents…and that the gibbering mouther was no mouther at all…
Space travel between the spheres is a complex endeavor requiring the song of an outsider (typically a lillend) to weave a sonic passage between the crystals that border the solar systems. Mortal magicians who make the journey almost never succeed. The space between the spheres is alive with…something…and the weave of mortal spell tunnels are too porous to keep fragments of the something out. These fragments are the shoggoths, who supply their own terrible, maddening song.
—Crucible of Chaos 29–31 & Pathfinder Bestiary 249
My coworker came back from vacation today wearing a Cthulhu fez. I can only assume that R’lyeh has great swag.