Spawn in stealth, but don't attack anything, even once attacked they remain passive until they're dead. Even saw NPCs attacking one like this.
I can confirm this, re: "don't attack anything".
I've seen this happen once too. NPC attacking it and it doesn't fight back.
Let me know if this is still happening.
Nope
meet a hunting spider came up behinde me and slit my pretty lil throat wide open
Oh God, I wish they had used stealth in the UD. That would have made them ten times more scary than they already were.