Night Stalker
Something many-legged that comes out after dark, and never quite the same thing twice. It spits web, fire or stone.
What a stalker looks like is a property of the world: every planet randomly generates its own kind, so all of one world's stalkers share a build (how many legs, how long, what colour, what they spit) and the next world's are their own. What's fixed is the idea: a body slung low between legs that arch high at the knee, something with a face on the front, and a will to come at you after dark.
It walks properly: each foot stays planted until the body has carried it too far, then steps, with four feet always down. It climbs a step by reaching a foot up onto it first.
Its spit
Thrown ahead of where you're going, in an arc you can read and sidestep. See Webbed and Burning for what each kind does.