I like the "Omega Clouds" found in Jack McDevitt's novels. Sweeping in waves from the center of the galaxy along the galactic arm every 8,000 years or so and devasting any objects that contain right angles (hence wiping out whole civilizations as they move outward). In McDevitt's universe humanity is the only known interstellar intelligence but there are remnants of interstellar civilizations (now dead) found up and down the Orion arm.
They are enigmatic, implacable and, frankly, omnipotent. They act as a force of nature. I always thought it would be a great campaign to first discover that they exist, then calculate that they come in waves, then finally try to find out just what (and why) they are.
Not a great foe you love to hate but rather a great dangerous mystery to resolve (or avoid).
They are enigmatic, implacable and, frankly, omnipotent. They act as a force of nature. I always thought it would be a great campaign to first discover that they exist, then calculate that they come in waves, then finally try to find out just what (and why) they are.
Not a great foe you love to hate but rather a great dangerous mystery to resolve (or avoid).