Invaders out of space appeared after a falling star blazed down from the cosmos. These alien beings have an unsettling habit of appearing between glances and silently watching. Invaders stand upright like a biped, shrouded in what are either voluminous robes or draping folds of skin.

Observers who are lucky find the invaders gone in a blink, and those who aren’t so fortunate hear the bloodcurdling hiss these things from beyond the stars emit as they attack. All that remains of their victims is a spray of gray powder amid crumpled clothing.

Secret.

The invaders have little resilience to the toxic and virulent threats of the Material Plane, and they succumb quickly to diseases and poisons.